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i'MT^'-*" • *n ^ii_ 











. f « r 

• t^* * 
G. GREGORY, d.d. 

« AVTHOR or 



Vol. II, 

J, O N D O Nt 

f KIKTSe r»» J« JOMJOK, »» 7*» "• TAW*'» «•««» »*■»» 


90LD BY OKem OF Till 



Book VL 


Chap. L— page i.' 
Of SalU in general. 
DefinitioM of Salt s,-^S alt sfimple and amp^ni.^Wbat ar$ caUfd 
Jimple Salts are in ndity compound Bodits.'^Oxygin$iu 
. frinciplt. 

^^ c H A P. li. 

;; * Alkalies.— page y. 

1;^ Mimral fixed Alkali ; where found.— Vegetahle fixed AlkaU ; 
hnn ebtained.-^ U/e of the fixed Myites in the Arti,—Ufe of 
^ AlkaUs in making Glafs —Proce/s of making Soap — Volaiik 

^ AUtedi ; bvw obtained i a compound Body. — Alkaline Air. ^ 

Chap. III.— page ii. 

Of Acids in general-^Fitriolie Acid ; bvw obtained^ fcTr,-^ 
Nitrous Acid I bow obtained.^^Murlatic Acid; bbw obtaimd^ 
and its Vfe in the Arts.-^Fluor Acid ; diffohues Glafs ; em- 
ployed to make Etchings on Glafs^^Acid of Borax^^Pbof 
pboric Acid.— Acid of Amber. 

C H A p« IV.— page »3. 

Neutral Salts. 

fbi Union of am Acid and Alkali deftroys the corrofive Quality of 
oacb.^Neutral Salts do not eoamumicaie the f dim Quality to 
itber Bodies.'^CfyfialUste Formi bow decompofed. 

Pi % Chap. 



Chap. V.— page 25. 
Vitriolic Salu. 

^lauMj Salt ; bow decompofid ; Solution of it left to cool crjf- 
talltzes on being Jbahtn^^-^Vitriolated Tartar^-^Fitriolatid 

Chap. VI. — page 50. 
Nitrous Salts. 
Common Nitre ; Phenomena attending its Deflagration with infl/tm^ 
mahle Suhflances.-^Natural Hijlory of Nitre, — Cubic Nitre* 
-^Union of nitrous Acid with various Earths^^-^Nitrous A/n^ 

C H A Pf VI T.— page 38. 
Muriatic Salts. 

Sal Digejlivus, — Common Salt, — Rock Salt, — Natural Hiftory of 
Salt, — Saltnefs of the Ocean. — Ufes of Common Salt in the 
Arts.'^Sal Ammoniac* — Natural Hiftory of Sal Ammoniac, 

Chap. VIII. — page 51. 
CombiDations of the other Mineral Acid<. 

ffarry Tartar, '•^Sparry Soda,'-^Borax ; its Properties ; its TJfe 
in the Arts ; Combinations of Salts with Metals, 

C P A p. IX. — page 55. 
Earths in general. 

^ive Kinds cf Earth.'-^Deflnition of Earths, — Exceptions,-'^ 
Other general Properties of Earths. -^Calcareous Earth. — 

Chap. X. — page 61. 
Calcareous Earths. 

Chalk^'-^Limeftone. — Marhle.^^Marle. "^Calcareous Spar. — Ice- 
land Cryftals.-^Petrif actions. '^Parts of Animals found jn 
Marie, iffc^^GypJbms.-^Great Farieties, — Alabafter.^^Fi' 
ir$us ' Stone^-^Mineral Glafs^^eknite*^^Gyp/eQus Spar.^^ 



rlaifiir ef Paris i bow prtpartd.^^'BuJihU or Derhyjhiri 
Spar*^^Span\ how formed^ — Beautiful Appearances in 
different Caver/u.^Metallic Combinations *wiib calcareous 

Chap. XI. — page 74. 
Magneiian EartAs. 

Magnefia\ ho^m obtained j^^Ep/om Sait.'^Soap Rock.^ French 
Chalk — Serpentine Stone.^^Mica.-^Talk.-^Mufco^vy Glafs. 
^^AJhtftos. '^Mineral Cloth ^^^Mountain Leather. ^^Mountain 
Flax.^^Mountain Wood* 

Chap. XII. — page 80. 
Ponderous Earth. 

Barytis a /carte Mineral ; found in two States.'^Criflatwaj'^ 
Ponderous Spar.'^^a'wkt-'^Li'ver Stone* 

Chap. XIII. — page 82. 
Argillaceoas Earths. 

Gemral Account of Clays or Argils. — Alum ; /// Compofition.''^ 
Natural Hiftory of Alum. — A3ion of this Subftance on other 
Bodies. -^TJ/es of Alum in the Arts.^^Lac Luna. ^'Porcelain 
Clay. "^Manner of making different Kin(ts of Pottery '^Stone 
Ware.^^Tello'W, or ^een^s Ware. — China. — Lithomarga.-^ 
Terra Lemnia.^^Bole.^-^Zeolite.'^^Lapis Lazuli. -^Tripoli.^^ 
Brick Clay.^Slate. 

Chap. XIV.— page 98. 
. Siliceous Earths. 

General Arrangement of Flinty Subflances.''^^ems.^^Diamond,'^^ 
Ruby.'-^ Sapphire. — Topax.^^Emerald.'^Hyacynth.'^Ame' 
thyft.'^Garnet.'''^Tourmalin.^-'OpaL^^CompoJition and Pro- 
perties of precious Stones.-^^artz.^Rcck Cry/la's .'^Pebbles. 
'•^Flints.'^Lapis Nephriticus.^^Cat^s- Eye.'^Hydrophanes.^^ 
Explanation of the Phenomena of the Hydrophanous Stone.^^ 
Moonr S tone. --^ Chalcedony. — Onyx.^-Camelion '^Sardonyx, 
^^Agate. '^Common Fhnt.^^Chert.'^Sand and Gravel"-^ 
Jafpir.-^Fddt Spar. ^Labrador Stone.^Sihirl and Whet^ 
A 3 flonc 


Jl9n$.'^Jn of making dafi.'^PrUci RufmU DrQp end 
fhiUfrfhictl Fhial.'^Curiotis Pbtnomenon* 

^ Chap. XV.— page 117. 

Cooiponod Earths. 

DtfinitioH 9f this Gtmu^'^Farious ecmpomnd Stouts, 

Chap. XVI. — ^pagc 120. 
Volcanic Prododts* 

l0wa,'^»Different Kinds. ^^Frogr if s of a Rivtr of Lavu ^^Com-' 
pound Parts of La'ua.^-^Pumici Stoni.-^Bafaltisv^Trapp.'^ 
Terra Puxxclana^ 

Chap. XVII.— page 125. 

tjyks of Mttals.^^Tbiir Propertief.^Weight^ Opacity , MalleaU* 
Jitjt Dudlility, Fufibility. — Mix lAjitk iich otber.'^Tbeir 
JnfiamsnabiUty^ — - Calcination, -— Entire and Semi-metals •'-^ 
PerfeU and imptrfea, -^Natural Hijlorj of Metals, — Working 
of Mims^-^Affaying-^Smelt'tng^-^lJnion nxitb Acids^^^ASion 
of otber Subjlances on Metals, ^ 

Chap. XVriL— -page 138. 
Natural Uiftory of Arftnic, — Mode of nducing it to the metallic 
Form^'-^White Enamel, — Orpiment.'^Realgar,''-'lts ^je in 
Medicine,'-^ A dreadful Poifon ; bow to detect it in tbe Bcdy.^^ 
A Remedy for tbi Poifon ofArjenic, 

Chap. XIX.— page 143. 

Short Account of this Semi^metal.''^May he reduced to ttn Acid."^ 
Afcarce Miner aU 

Chap. XX. — page 144. 

The OnofTungfiein confounded with tbM of Tin,^^Wbere fouad. 
'^^Mode of reducing it to the regulim or metallic State. 

% Chap. 

C UT E. H, T.S,. ^ 

Chap. XXI.«*page 146* ^ 


Htinral Hijtory of Ma$iganrfi.^tu Effi3s $n Gla/s.-^Reguttu cf 
Mital.—Biack Wad.—MMgM9f$ eontaimd in Figitabltt<^ 

C H A F. XXII.->^page 149. 


Natural HiJIofy %f Nickel — MeoJ how obtained.^'DitonatU 
nmtb Nitrt.'-^Has a firong Ripulfion for Silvir, and Attract 
Hon for $Mlpbur*-^J uftlefs Minoral. 

C B A>. XXIII.«-i»ptge 152. 

Natural Hiftor) of Cobalt. — Analogy between tbU Metal and tbi 
blot colouring Matter of Vegetables* — Mode of ]ffaying it.^^ 
Mines of Cobalt -^Smalt, or Powder Blue.^Ujh ofCobak 

in the Arts. — Curious fympatbetic Ink.'^CbangeeMi Land* 

fcaptif^Union witb other Metals. 

Chap. XXIV.— page 157. 

External Qualities of Bifmutb.'^ A powerful DiJJfblver rf Earths. 
m^Fearl Wbite^ a pernicious Cofmetic,~^urious Experimeni* 
— ^ metallic Compojttion, <wbich melts in boiling Water*^^^ 
Various Ufes ofBifmutb in the Arts* 

Chap. XXV.-^page i6a. 


Natural Hiftory of Antimony.^^Regtdus.^^^Snow tf Antinsony^^'^ 
Calcination of Antimony. '^Combinations .with Acids.'^Butter 
rf Antimony.'^Antimonial Wine.^-Vfes tf Antimony in Medi^ 
eiui.'-^Floros Antimonii. — Glafs of Antimony. ^^Crocus of An* 
titbany.—Sulpbwr of AKtimony.^Tartar imttke^James^s 

A 4. Chap. 


C H A r. XXVI.— page 170. 

GeniralDt/cripthn rf Ah MeHd.-^Pbihfipbtr^t WcoL^Umok 
with Acids j^Wbiti FitnoLm^Dii^ation ofZimc with Nitri. 
^^^ombinathn with Metals. '-'Pewter.-^Its Ufi in Fin^ 
'Wcris.'^Natural Hiftory of Zinc.^^alandnij-^Black Jack. 
'•^Bra/si bow madi.-^Tuttyj^^FiMehieck* 

Chap. XXVIL— page 177. 

Ixtinfive Utility of this Metal^^Its Properties, — Natural Hi/- 
tmy of Iron.^-Eagk'Stones,'^Blood-Stones, — The Loadftone. 
-^Emety.'^Ochres.'^Smelting of Iron.-^Forging of Iron.^^ 
Making of SteeL-^tempering of Steel. — Caft SteeL^^Great 
Dijpojition in Iron to unite ivith other Bodies, — Green Vitriol, 
bvw proeured.'^P ruffian Blue,--^Ink,^-^InJlammation of Sul- 
fhur and IrOtt.'-'^Tinning oflron.^^Preparations of Iron ufed in 

Chap. XXVIIL— page 19$. 

General Properties ofTin^-^Granulaied Tin.-^Natural Hifiory of 
7in**^^Its Union 'with the Acids. ^^UJe of Tin in improving 
the red Dyes^^-^Smeaking Liquor of Liia'vius.-^Aurum Mufi^ 
nsum.^-^Combinations of Tin <with other Metals .'^Different 
Species of Pewter^^^^Putty^'^Application of Tin in dying.-^ 
Ufi in Medicine. 

Crap. XXIX. — page 202. 
. Lead. 
Gtmred Properties of Lead.^^Red Lead, — Litharge, — Natural 
Hifiory hf Leadj-^Smelting Lead Ores,^XJnion 'with Acids. 
^—Plumbum C^meum.^^White Lead \ ho^ made. — Sugar ef 
Lead.'^Union nviih other Metals. — Common Solder. — {/>j of 
Lead'-^Greai Danger from leaden FeJels.'^De^onfi?ire Colic. 
'^Means of deteBing Lead in Liquors. ^^Medi col U/es ofL^ad, 
'^Ufes of iU Calces in tihe Arts* 




Chap. XXX. — pkgt 213. 

Gemral Froftrtus of C^pptr^-^Its Natural Htfiorj. — Turqti^Jk 
Gem,'^^S milting and refining of Copper.^'Aatiqms Slatugs 
prefimfid by tbt Green Ruft^-^-^Jnion with Adds. — Bhe 
FitrioL'-^olouring of Guns.^^Cuprum AmMoniacum.^^Ferdi^ 
gris.^^Union tvith Maais, — White Copper* — PimMuL-^^ 
Gun MetaL-^Bell MetaL^^Metal of ancient Statuej.'^-'BroMZgm 
^'Speculums of Befle^ingTelefcopes.^^Pot Metal^^^TiumiMg cf 


C H A Pw XXXI.— page 226. 


Great AttraBion of this Metal for the Matter of Heat.^^^uui^ 

flnjer% rendered folid \ malleable. — General Properties ef 

^ickfil'ver.—Hydrargyrus calcinatus.— Natural Hifi^rj rf 

Mercury.^Cinnabar.'^Nati've Vermilion, — Aaion rf Addt 

on this Metal — Turbitb Mineral-^Red Precipitate --^fFhite 

Precipilate.-^Corrofive Sublimate. — Calomel —Keyfer's Pills. 

' '^Ethiop's Mingral.^FermilioH.'^AmalgaMs.'''^old madt 

brittle by Mercury. ^^Mode of gilding MetaJs.-^Ufe of ^ick- 

filver in extraBing the precious Metals from the Earth, 

Making of Looking Glajes. ^Conditions necejfary for tbt 
Operation of Mercury on the hum^n Body. 

Chap, XXXII.— -page 239. 

CharaBer of the perfeB Metals.— General Properties cf Siher.^^ 
Vegetation of Sil'ver. -^Natural Hiftory ofSil'ver.—Afaying of 
Sil<ver.—Cupellation.— Lunar Caufifc— Fulminating Silver. 
— Luna Cornea^^Diana^s Tree. — Green Gold. — Standard 
Siher Coin.'^ Plating ivith Siher ; honv performed.^^French 

Chap. XXXin.— page 253. 
General Properties of Gold.— Gold calcined by EUBricity .-^Ex* 
trem Duffility of this Metal.-^Natural ffifiory tf Gold.^ 
» Procefis 


Fr9€ijjlts fw feparating GM from other Su^ancest^mm^juarim* 
tioiU'^Tbi Tonehfion€.''^Aqua Rigia^^^Rio/ims tvly ibe diffe* 
rent Acids a& on metallic Bodies. ^^Fulminating G#A/.— /'at* 
fie Powder of Caffins.^^Golden Calf^ ho*w deftroyed by Mofee^ 
^^Vnion of Gold iJaith other Metals.'^Standard Geld Coin of 
different Countries, t 

C H A F. XXXIV.— page 266. 

KeUured Hiftory of this curious Metai>-^Its Properties. '•^The mojt 
ponderous Body in Nature.'^^Its Uardnefs and Infufibility,^^ 
Soluble only in Aqua Regia emd oxygenated muriatic Acid,^^ 
Its Union nuith other. Metals, ^-^rucibles formed of it. -^Might 
hi applied to variotis Ufes mahich no other Metal can emfwer* 

Chap. XXXV.— page 271. 
Of inflammable Subfiances ia general. 

Ignition and Comhufiion defined^'^Acids formed by the ComiuJHom 
mfinfiammable Subftances, — tlamt ; how produced* — The Ob- 
je£i oftheprefent Inquiry kmited.^^What Subftances are com- 
monly termed injlanmable* 

Chap. XXXVL— page ayj. 

thofphorus of Knnkel-^Light from putrefcent Suhftanees.^^uri* 
ousFads. — Light from the Sea Water ^ \^c,^BoUgnian Stone, 
— Baldwitt^s Fhofphorus.'^Phofphorus of Homberg,'-^Pjro^ 

Chap. XXXVJI.— page 289. 

Citneral Properties of Sulphur,^ Natural Hifiory of Sulphur ^-^ 
Union with Earths, ^^IFith Alkalies. ^-Li^er of Sulphur.'^ 
Artificial fulphureaus Waters^-^Ujes of Sulphur, , 

Chap. XXXVIII— page 253. 
The Carbonaceous Principle. 

Kaiure ofth^ Carbonaceous Prhtciple*^^h what Suhfiancet priio>» 
eiptdlj fouad.'^CharcoaL'^Lamf*bleuk ^ '' ^r en g AttraBitm 


tfthi Carhmaciws Principie for Oxygnt.'^hs U/e in "the Ri^ 
iu&ion of Mftals.-^PIuMit^, or Black Lutd.'^lts nmrious 

C H A F. XXXIX.— page 297. 
f itcoal. 

Difftrmt Species of Coal ^^Newcaftii CoaL'-^Cm/m.^^jtateCaaL 
^^CoHutl CoaL'^^Kilkemty Coal,^^Bovey CoaL^^Peat^*^ 
CoJU.'-^oal Tar, -^Natural Hiftory of Coal*^^J^firvatiotu 
relafive to the Del»ge» 

Chap. XL--— page 308. 
Napkta^ Petrokom* Barbadoes Tar, &c» 

Nature and Properties of Napbta^^-^Bumin^ Fountains. '^Petro'^ 
leum.'^Mineral Pitch, or Bariadoee Tar.^^Lake A/pbaltei.*^ 
Afpbahum ; bow colUaed^^Elaftic Bitumen.^^Componeut 
PrincipUs of thefe Suhfiances* 

Chap. XLI^— page 311. 
Jety Amber, Ambergris, and Miaeral Tallow. 
General Properties of Jet. ^ Its Nature and Origin.— Jmher.^ 
Acid of Amber.— Natural Hifiory of Amber,— Different Opi^ 
neons of its Origin.— Ambergris.— Its Natural Hifoty.— 
Mineral Tallow. 

Chap. XLIL— page 317. 
Of the Diamond coniidered as an inflammable SubHance. 
Experiments proving the inflammable Nature tf tbe Diamond.-^ 
Experiments ofM. Cadet — OfD ^ Arcet.^^Vital Air neceffary 
to tbe CombufiioH of tbe Diamond.— Experiments of Lavoifier. 
^Purtber Experiments. — CorMuJionfrom tbe nubole. 

Chap, XLIII.— page 320. 
Tbe Struaure of the Earth. 
Tbe Curiojsty of Man in this Topic limited by tbe Weaknefs of bis 
Powers.— Tbe Body of tbe Eartb difpofedin Strata.— Declinn^ 
ties of Mountains.— DiJ^ofition and Order of the Strata.— Cd^ 
dj JJland.— Where UetaU are ufuedfy found.— Probable Statt 


. if the Earib at its Cnatioiu^^LtffOts hj which Alterationi 
nmuld be produced. — FoffilSbells^ i^c. accounted fw-.-^Forma- 
tiom of IflandSf iic-^Other Irregularities of the Earth's Sur^ 
face explaiuedm 

Chap. XL1V.«— page 350. 

DifiinBion between Hills andMo^tains.'^Mountainsfriwuevaior 
feceudary.^^'Gramte Mountains onlyfufpofed in general prim^' 
^aL'-^Some Limeftone Mountains primaH/al.^^Jllu^ialMoun- 
tains.'-^Entire and firatified Mountains. ^^Mnmtains bomoge^ 
tains. — Height of Mountains i bonv mea/ured^^Computed 
.Heights of the mofi remarkable Mountains j^Line ofCongela* 
tioM in different Parts of the World. 

Chap. XL V.— page 357. 

^ " Volcanoes. 

Central Ot/er'vations on Volcanoes.— Their ConneBion with the 
Sea. — Immenfe Force of fubt erroneous Fires exemplified in ma" 
rious Ufiances. — Theory of Volcanoes. — Great Depth — traces 
•f Volcanoes in different Farts of the World j^Defcription of 
^tna^^^Eruption ofVefwuiuSt in 1 794. 

Chap. XL VI.— page 406. 

ConneBipn bettueen Earthquakes and Volcanoes.^Earthquakes 
cau/ed by the Progre/s of Steam between the Strata of the 
Earth.Signs of approaching Earthquakes.— Great Earths 
quake at Lijbon, in l7SS*—Farthquakes in Calabria, in 



Book VII, 


Chap. i.-7-page425. 
Of Water io general. 

Water a compound Body^i^^Tbree Stata of Wattr,^^ Water in m • 
fimid State .'-'^Florentine Exferiment*'-^ Fa fonr,^ Experiments 
afiertaining the Force of Vapoun^-^Sttam Engine^^^ct*"'^ 
Phenomena of Freezing.^'^f Thawing. '^^Water expanded in 
the State of Icej^^Immenfe Force exerted by Water on puffing 
to^ that Staie.'-^Why Ice is net perfeRly tranf parent. 

Chap. II^— page 450. 

pifcoveries of Jrchimedes in this Branch of Science. '-^Of thi Mo^ 
derns^-^^Honv Fluids are aSed upon by the general Laws of 
Grctvitation.'^Particlei of Fluids taS independent fy of each 
etber,n^Experiment a/certaining this PrincipUj^^Fluidsprefs 
equally in all DireSions. 'Cautions necejfary in^conftruBing 
Aquidudst ftfr. to guard agdinfi the lateral Preffure of Fluids."^ 
All Parts of the fame Fluid in Equilibrium nnith each other. ^^ 
Snrfaces of Fluids always in a Plane parallel ^ith the Hori- 
xon.'^PfeJ/ure of Fluids in proportion to their Height, •^Ifydro^ 
ftatic Paradox, •'^Effcds of Gravity on Fluids of different Den* 
fities,*-^A£lion of Air on the Surfaces of Fluids, — The Siphon. 
•-^ABion of Fluids onfolid Bodies immerfedin them* — Why cer^ 
tain Bodies fink and otherifusim in certain Fluids, ^-^Bodies thai 
fwim dijplace a Bulk of Water equal to themfel'ves in Weight 
but not in Magnitnde.'^The fame Body mjill fink in one Fluid, 
which willfwim in another, ^^The Hydrometer.'-'^Fahrenheit^s 
Hydrjdmeter,-^Recapitnlaiion of the OoQrints rejpeaing fpecific 
G/a*oity,-^How to make a Globe oflronfiwim en the Surface of 
• fFcUer.'^Boats made of Copper. 

Crap. III.— page 480. 

Of the Difcharge of Fluids through f mall Apertures. '^The Dif- 
charge ^Fluids through fuccejfive Pifes^^^Artificial Fountains. 



.— Pjob^/.— T'i&tf Raijlng Pump.— The Forcing Pump^^^Tbi 
Sucking Fump.—7\e Compound Pump-^The Fire Engine.— > 
Motion of Water in . Conduit Pipes,'^ 0/cillatory Motion of 
Water in a Sipifoa, — Ofcillatory Motion of Waves. •^Motfom 
of WbeeU aQei upon hj Water ; and ConftruBion of Water 

Chap. IV. — p«gc 531. 
Of the Ocean. 

Ssltnefs of the Ocean.^^DiJferent Opinions as to the Caufe.^^Pro* 
hahie Reafons *why the Sea has been al<ways falt,^^Temperaturi 
of the Sea at differtnt Depths.^^Modesofren!^ing Sea^nvater 

C H A r. v.— page 540. 
or Rain. 

fticerfitnlatioie of DoBrints felasi've tofpontamosu Evaporatton,r^ 
Vaponr by fomi fuppofed to cmtfift of hoUow VeficUs.-^Rain.^^ 
9ijferent Theories of Reun,^^-^Snow,'*^Hail,^^Rain nvhicb 
froxe in coming in centaS ivith the Earth^^-^Large Hasl^ftonesm 
r-^Fogs.''^Dt'w,**^Hoarfroft, — Injtances of partial freixing 
K»h^n the general Ttmptratuft is above tbefrtetang PoinU 

C h A p. VI.— page 551. 
Of Springs and Rivers. 

Origin of Springs. ^^Digging of Wells, ^^Natnre of Springs. ^m 
Mnrjbei.^ Cheap and eajy mode tf draining them,-^Intermii'» 
(ing Spring*- — River s,^~-Their Source ^ bfc* 

Chap. VII.— page 565. 
Hot Spring*; 

frohable Caufes of thefe Phenomena.— Jbound moft in nsoicanic 
Regions. — Hot Springs in Icelatii, neat' Mount Hecla.^^At 
G^fer.—ln the Ifland ef Ifihia.—At Fiterbo.— Explanation 
of thefe fbenomena^—Bntming Will in LancaJbire.-^Explaittm 

C » A p. 


Chap. VIIL— page 571. 
Mineral Water?. 

Ctip^ty pf Water us a Sel'uinf.^^SuhfihMcet commonly found in 
Mimral Watiru^^tixid Air^-^Mineral Acids ."^AlkaUnt 
Sabs.^-^JfsuirsJ Salts.-^partfy SnbJtanas^'^Sulpbur.^-^Mi* 
iats.'^^Modo of oxanuning and smsdjxing Mimral Wattrs.^^ 
• Chomical Tefis^f^Analjfis ofthi moft ceUbrmed Mineral or Spes 
Waters.^^AiX'la-Cbapelle.'-^Batb. — BriftoL — Buxton.*^ 
Bcarborougb.'^Sfa.'-^Refleaions on tbe Ufitf Mineral Water 
in g0neral. 


Book VL 

of mineral substances, and. the 
structure of the earth. 

Chapter I. 


Definition of Salts* — Salts fimple and compound.^-What art called 
fimpk Salts are in reality compound Bodies ^^-^Oxygenoue 

THOSE iubftances arc denominated falts which 
arc fufiblcj volatile, foluble f in water, not 
inflammable, and fapid when applied to the tongue* 
The moft fimple ftate of falts, is a mafs, white, 
bricdc, and in fome degree traniparent. Salts in 


* This part of the work will ncceflarily be in foir.'? mea- 
iUre chemical ; but it is only by chemical procefs that we cad 
reach the conflitaenc particles of natural bodies. The reafoa 
of this arrangement will be obvious. The objed of this book 
is to treat of the ftruflure of the earth ; but it Is neceilar/ to 
be iirft informed ooncerning the diilercint matters of which it' 
is compofed* 

•t The diftin6Hon between folution and mixture has been 
already ftated ; but it may not be improper to reniind the readcN 
that in folution the body which was iolid is fo completely in 
union with the fluid pr menflruumj that the compound is com- 
pletely tranfparent, though not always colourlefs. Common 
falt» for inflance^ with water, makes si colourlefi folution; 

V01.JI, B »»»« 

2 Cf S4d$sJimpU and compound. [Book VL 

certain degrees of heat are fluid and tranfparent^ 
like oiL They differ in their degree of fufibility 
and voladli^. Some aflume the form of vapour 
in the ordinary temperature of the atmofphcre, 
others in a great degree of heat remain fixed; 
Previous to treating of the particular fubftaftces of 
this clafs, it will be proper to make a few obferva- 
dons on the formation of faks in general. Salts 
are either fimple or compound. Simple lalts are 
diftinguiflied into alkalis and acids i and from the 
union of an acid and an alkali are produced com- 
pound falts, which are alfo called neutral, becaufeby 
this combination the charafteriftic properties both of 
the acid and alkali are loft, and a new body is. 
formed, which is extremely inert, in comparifoA 
with the two fubftances of which it is compofed* 
Several of the earths and fome of the metal§ arc 
alfo capable of being united with acids, and the 
compound fprms a fait more or lefs perfeft. 

Alkalis and acids, at the time they obtained the 
name oi fimple (alts, were fuppofed to be really 
fuch ; modern difcoveries, however, have now led 
Co a different conclufion, and left no reafon'to 
doubt that all the acids, ^d at lead one of the al<- 
kalis, are compound bodies. The doftrine of the 
formation of acids is now folly elucidated ; the 

but blue or green vitriol makes a blue or green foladon 
with water. A mixture on the contrary is always moddy, and 
if left to Hand, a fediment ^ill be deposited. The point, of 
jfaturatktt is when the fluid will hold no more of the folid^bod/ 
in clear folution, bat fruifitatn i^ or ku it fall to th0 



Chap. I.]' Potmattmtf Acids* 5 

procefles of combuftion^ arnd of the calcination of . 
metals, which were formerly attributed to the exr 
pulfion of an imaginary fubftance> called phlogifton; . 
are now proved to be only the formation of acids ; 
or the union of the principle of acidity or oxygen 
cpntained in the atmolphere, with fubftanccs, the 
particles of which have, in certain circumftances, a 
ftronger attradtion for that principle, than it has for 
the matter of heat. The chief circumftance -which 
favours the union of the principle of acidity, which 
is alfo called by the French chemifts oxygen, with 
other bodies^ is a proper degree of heat; which,^ 
by removing the particles of bodies further from 
each other, diminiflies their attra6tion, and allows 
roojn for the entrance of air into their interftices. 
In the calcination of metals, and in combuftion, the 
oxygen gas of the atmofphere is decompofed, and 
while the'bafe is attracted by the inflammable fub- 
ftancc or metal, the ^natter of heat is difengaged, 
and becomes fenfible. Bodies, however, may be 
acidified or oxygenated without being expofcd to 
the air j and this is per^rmed by placing them in 
contaft with bodies which are already united with 
oxygen, but which have a weaker attraftion for that 
principle than the body which is tb be acidified. 
It is upon this principle that metals are deprived 
of oxygen, or reduced to the metallic ftate, by 
heating them in contaft with charcoal, tallow, &c. 
In this cafe the inflammable fubftance having a 
ftronger attraftion for oxygeii than the metal has, 
becomes oxygenated ^ while the metal, by being 
deprived of this principle, is reduced to the me- 
;:. ' J B a tallic 

4 Urn Rufi is generated <m Iron. (^Book VL 

talUc ftace. Metak and combuftible bodies may 
alio be oxygenated in the humid way, by fubmit- 
dng them tx> the a&ion of acids. In this procefs 
the acid furnifiies the oxygen, and is therefore de- 
compofed. The oxygenation of minerals in the 
bowels of the earth is probably chiefly effedted by 
the decompofitio'n of water, which is a compound 
of hydrogen and oxygen. A procef^ of this kind 
is continually carried on before our eyes ; the ruft 
which Iron acquires by being expofed to damp air 
is an oxygenation of that metal. Other metals, 
however, have Ids afiinity with the principle of 
acidity, and this is remarkably the cafe with the 
perfeft metals, platina, gold, and filver, which 
therefore do not become ruftcd by expofure to 

In treating of falts, I fhall firft give an account of 
the alkalis, next of the acids, and laftly of their 
combinations, or the neutral falts. 1 fhall defer 
fpeaking of the earthy and metallic falts till the 
earths and metals ar^ dcfcribcd. 

Ch A^« 

Chap; a.] [ 5 3 

Chap. IL 


Mineral fixed Alkali ; nuhere found,'''»V$getable fixed Alktdii 
b(yw obtained. — V/e of the fixed Alkalis in the Arts.^Vfe of 
Alkalis in making GlafA^FroceJs of making Soap.^^Volatile 
Alkali i hoFW obtained \ a eompourtd Bcdy*--^ Alkaline Air. 

MI NERAL fixed alkali, foda or natron, is 
the fait which is found recorded in ancient 
hiftory under the name of nitre. It is faid to be 
found in Egypt in tolerably pure cryftals, and alio 
in Perfia, where it appears in a form refembling that 
of hoar froft. Even in Europe it is found in fmall 
quantities in mineral fprings, and alfo on the fur- 
face of new walls, in the form of a dafnp and dewy 
efflorefcence. In a compound date it is found in 
abundance j it makes half the weight of common 
fait, and is alfo occafionally found naturally combi* 
nedwith other acids. The mineral alkali cannot be 
o\)tained from the native falts containing it, with*, 
out great labour and expence : what is ufed in the 
arts is procured by the incineration of certain 
plants growing near the fca-fide. The crude mi- 
neral alkali in commerce is called foda or barilla* 
Alkalis are cither mild or cauftic j the latter is tlicir 
moft fimpl^ ftate, as when mild they are united 
with the carbonic acidj with which dicy form a 

B 3 kind 

6 Dijlmguijhing Marks of Malts. [Book VI. 

Jcind of neutral fait. Though the carbonic acid has 
lefs affinity with the alkalis than any other acid, yet 
it is difficult to feparate it entirely. The ufual me- 
thod of accomplilhing it is to difTolve the mild al- 
kali in water, to add to this folution fome quick- 
lime, and then to filtrate the liquor, and evaporate 
it in clofed vcffcls ; the faline fubftance left after ^ 
evaporation is an alkali almoft entirely deprived 
of carbcnic acid. This procefs is founded on the 
greater attracLiori which the carbonic acid has for 
quick lime than for the alkalis. 

The VEGETABLE fixcd alkali, pot-afh or kali, 
Agrees in feverarcircumftances v.'ith the former. It 
is acrid when applied to the tongue, requires as great 
a degree of heat to melt it^ and in a very ftrong 
heat flies off totally in vapour. It diffisrs from the 
folTil alkali in having a much ftronger attraction for 
-wate^ TWs alkali may be cryftallized, but not fb 
cafily as the foffil. Little of the vegetable alkali 
has been found in a ftate of nature, and that only as. 
entering into the compofition of nitre. It is ob- 
tained in confiderable quantities from the aftics of 
almoft all land vegetables, by infufing them in 
water ; the liquid, when ftrained from the dregs, 
will Ihen contain the fait in a ftate of folution, and 
by evaporation we obtain the dkali in a folid 
form. It is alfo eafily obtained from a fubftance 
called tartar, which is depofited by wine. The 
properties and ufes of the vegetable alkali ar^ very 
fimilar to thofe of the mineral. 

The fixed alkalis are employed in fcvcral of the 
arts^ and particularly in tliat of making glafs ; for 


Chap* 2.] Mamfalfure tfScap^ 7 

though many fubftanccs will fufc the vitrtSabfc 
earths, and- reduce them to a kind of glafs> the 
alkalis are found the moft effedtual and convenient. 

In the foap manufa£kory al(b the alkalis are a 
-principal and eflcntial ingredient. Comnaon Ibap 
]& indeed a combination of fixed, alkali in a cauftic 
ftatc with fat and oily matters. A very fine fpecics 
of foap is formed by the union of mineral alkali 
with olive-oil, or oil of fweet ahnonds. In the 
making of this fubftance, the alkali is firfl: rea- 
cted cauftic by boiling it with half ic^ weight of 
quick- lime, which abftra€ls its carbonic acid or fht- 
cd air by fuperior attrattion. What is called fpap- 
leys is a folution of the cauftic alkali in water, which > 
©evaporated tofuch.adegreeofdenfity as to be able 
to fuftaina new-laid egg. To make the finer ibap^ 
a part of this lixivium is to^be diluted, and mixed 
with an equal quantity of olive-oil. The mixture 
is put on a gentle fire, und agitated, by which the 
union is accelerated. When the mixture begins 
to unite well, the xdk, of the lixivium is to be ad** 
ded to it, and the whole is to be digefted with a 
gentle heat, till the foap is completely made. 
Good ibap of this kind is Wjhite and firm when cold, 
an4 is not liable to become moift on expofure 
to air; it is entirely mifcible with water, to which 
it gives a milky appearance, without exhibiting any 
particles of oil on the fiyfiice. 

In the making of foft, liquid, green, or black 
- foaps, cheaper oils are employed, as oil of nuts, 
of hemp, of fiihj^ &c. but tallow is the ingredient 
.ufed in our common hard foap. 

B4 OU 

« ^ VolattUAlkaU. [Book VL 

Oil may be feparated from foap by the addition 
of an acid, without being much altered in its pro- 
perties. On tKis account, waters which contain 
any acid, either in a difengaged ftate, or combined 
with any fubftance except fixed alkali, decornpofe 
foap, and will not completely mix v/ith it. 

In this decompoficion, efpecially that efFefted by 
the vitriols of lime and magnefia, which are fre- 
quendy contained in water, the vitriolic acid unites 
with the fixed alkali of the foap, and forms vitriol 
of foda, or Glauber's fait j the lime or the mag- 
nefia combines with the oil, and forms a kind of 
foap fcarcely at all loluble, which floats in a whitifh 
curd like maflfes on the fuiface of the water. 

The VOLATILE alkali or ammonia is feldom or 
never found in a fimple ftate. It is met with in 
nature only compounded with other bodies, in ni- 
trous ammoniac, or in common fal ammoniac, which 
is fometimes found in the neighbourhood of volca- 
noes, or coal mines which have burnt for a long 
time. The volatile alkali of commerce is chiefly 
produced from bones. This alkali is very different 
in its properties from the other two j its volatility 
is fo great, that under the ordinary preflure of the 
atmpfphere it is continually flying oflf in a very 
pungent vapour. It is fold in the ftiops under the 
name of fmelling falts, fal volatile, or fpirit of 
hartlhorn. The procefs of putrefadtion in animal 
matters, and in fome vegetables, particularly cab- 
bages, throws it ofi^ into the air, together with 
other volatile matters, which in fome meafurc dif^ 
guifc its fmclh Volatile alkali is now proved to 


Chap, a.] Volatile Alkali a ctmpeunS Suhfiance^ 9 

be a combination of two other* fubftances, hamely, 
the bafes of the azotic and hydrogen gaffes* M. 
BerthoUet has found by analyfis- that 1,000 parts of 
Volatile alkali confift of about 807 parts of azote, 
combined with 193 of hydrogen. The volatile 
alkali of the Ihops, that is in its mild and concrete 
ftate, when heated to a certain degree, affumes the 
form of vapour, but by a diminution of the heat 
returns again to the concrete form. Volatile alkali, 
however, deprived of the fixed air which rendered 
it mild, is capable of receiving a permanently 
claftic form; in which ftate it is called alkaline air* 
When a mixture of alkaline air and marine acid 
air was made by Dn Prieftley over mercury, a beau- 
tiful white cloud was formed, and a diminution in 
the bulk of the airs took place. The cloud hav- 
ing fubfided, was found to be common fal ammo- 
niac, or a union of the volatile alkali with the ma- 
rine acid. Nitrous air admitted to alkaline air, 
likewife occafioncd a whitifli cloud, which foon 
difappeared, leaving only a little dimnefs on the 
fides of the veffel. Fixed air admitted to alkaline 
air, produced a depofition of the common or con*- 
crete volatile alkali, in the form of oblong and flen- 
der cryftals, which crofled each other, and covered 
the fides of the veffel like a net- work. Inflammable 
air admitted to alkaline air, produced no particular 
appearance. Water abforbed th^ alkaline air, and 
left the inflammable air as before. Azotic gas feem- 
ed to have no effeft on alkaline air. Alkaline 
air is abforbed by water, in the proportion of ^ of 


»0 ' AlkalhffJir. [Book VI. 

an ounce mcafurc of aif toii grains of rain- 
water ^ and the water is by thefe means made prow 
digioufly ftronger than any of the volatile fpirit of 
fk\ ammoniac or bastihornj obtained in the cqox^ 
mOQ way. 


Chap- 3-1 [ II 1 

Chap. IIL 


Of Acids in generalj^^FiirioIic Acid\ how ehtained^ &r^,-w 
Nitrous Ai id \ bo^w obtained. -^Muriatic Acid \ how obtained^ 
and its Ufi in the Arfs.T-FIuor Acid; dijjhlves Glafs\ an- 
flayed to make Etchings on Gla/s,^^Acid of Boraxc^Fhoffhori^ 
Acid.'^Acid of Amber. 

ACIDS are very adive fbbftances, and when 
concentrated are highly^ corrofive. They 
have fo general a tendency to unite with other fub- 
ftanccs, that they are never obtained pure except 
by art. They are generally fluid, which feems^ 
. however, chiefly to be owing to their ftrong attmc* 
rion for water, of which few of them can be en* 
tirely deprived, and which they copioufly attraA 
from the atmofphcre. One of the marks by which 
the prcfence of uncombined acids may be afcer- 
tained, is their property of changing to a red, the 
blue colour of infufion of violets, which allcalis 
change to a green. Acids are diflinguiflied into 
mineral, vegetable, ' and animal ; tht fubje£t of 
this book win at prefent confine us to thofc of the 
firft cbfs. 

The acids found in the mineral kingdom are the 
carbonic acid or fixed air, the vitriolic, the nitrousjj 
the muriatic, the acid of fpar, the' acid of borax, - 
the acid of pholbhorus, and (he acid of amber. 


1 2 variolic cfAcid of Sulphur. [Book VI. 

The CARBONIC acid has already been treated of 
nxider the head of gafles. 

The VITRIOLIC acid takes its itame from vitric* 
or copperas, from v/hich it was formerly exti-adlcJ 
by diftUlation. In the new chemical nomenclature, it 
is with much more propriety called the acid of ful-- 
phtTTy as it is now found to be a cornbination of that 
mffammable fubftance with oxygen. The pungent 
and fufFocating fumes which are produced by the 
inflammation of fulphur, are an acid which is im- 
perfeft from a deficiency of oxygen ; and wliich 
cannot be condenfed without the aid of water. 
The vitriolic acid caji never be entirely deprived of 
%ater, bqt admits of the greateft concentration of 
all the acids> and may be reduced to a ftatc in 
which its fpecific gravity is double that of water. 
The dcrife and fluggifh appearance of the concen- 
trated vitriolic acid has given rife to the improper 
name of oil of vitrioU under which it pafles in the 


M. Lavoifier makes a diftinftion between this 
acid, as it exifts in an imperfeft and gaffeous ftate, 
and as it exifts in the form of a tranfparent and 
ponderous liquid combined with water. In its 
former ftatc he calls it, acide fulphureux (fulphureous 
acid) ; in the latter, acide futphurique (fulphuric 
acid). The fame difference of termination is 
employed to exprefs the different ftates of the 
nitrous acid, according as it is imperfeftly or com- 
pletely faturated with oxygen. A difFerence of ter- 
mination is alfo given to the combinations of 
acids, according as they are perfedlly or imperfeaiy 


faturated witli oxygen. Thus the combinations of 
the fulphuneous acid, are called Julpbites ; thofe of 
the fulphuric acidj /ulphats. Sec. . 

The vitriolic acid now ufed in commerce is pre* 
pared in the following manner:— A quantity of ful^ 
phur and fak-petrc, grofsly mixed, are placed in a 
velfcl within a Imall room, lined with lead^ and con^ 
taining a few inches depth of water at bottom* The 
fulpliur is lighted, and die room clofed. The f^lt- 
pctre krves to maintaih the combuftion, by the 
oxygenous gas which- it affords; and the acid 
fumes which arc produced are abforbcd by the 
water. The proccfs is repeated till the water is 
thought fufficieatly acid. The volatile fumes are 
then dilTi'pated by expofure to air, apd the acid is 
concentrated by diftilling off the fuperfluous water. 

The vitriolic acid is faid to have becomie cpn^ 
a«te by cold, but it probably was not in its mofl: 
perfeft ftate. It eafily parts with its oxygen to m^ 
flamnuble fubftancesf if oil is mixed with it, it is 
converted into a dark, vifcid fubftancci and emiO' 
Alphiireous and pungent vapours. 

The vitriolic acid has been thought to exift in 

the atmoiphere, but this is a miilake. It is difco- 

. vered in fome waters, but in fmall quantity | it 

exifts in fome ores pf metals, and makes one of the 

confiituent parts of gypfum. 

The NITROUS acid is a fluid of conliderablq 

weight, but does not admit of fo much concentra-- 

tion as the vitriolic. In its nioft pcrfedl form it is 

quite tranlparent and coburlefs^^buc in its ordinary 

: iWe ij is of an orapge tawny colour, and when^esC- 

. . * ' ' poled 

t4 ITitrms Acid of Aqua Portis. [Book Vfl 

pofed to the air it conftantly emits orjingc-colourcd 
fomes, which are noxious. It very readily parts with 
its oxygen to inflammable fubftanccs and metals j " 
and when mixed with oil of turpentine, it explodes 
and flames. The oil attrads the oxygen, and burns, 
*rhile the azote is fuddenly fet at liberty, and occa-. 
lions the explofion. When nitrous *acid, is diluted 
with an equal weight of water, it is called aqua 
fortis. The nitrous acid is confiderably difltifed in 
nature. All that is lold in the fliops is obtained by 
diftilling falt-petrc with" the vitriolic acid. 

Azotic and oxygenous gas were mixed together 
by Mr. Cavendifli, and the eledtric Ipark . was 
pafled through them. ' In thefe trials a dinainution of 
•bulk was always obferved; indeed five parts oif 
oxygenous gas being added to three of common air, 
almoft the whole difappearcd. By continuing his 
experiments, he found that an acid was produced, 
and that acid was the nitrous. 

The MURIATIC acid, in its ordinary ftate, is a 
yeflowifh-coloured fluid, and emits fumes which do 
not give the air a red tinge like the nitrous acid, 
but produces an appearance of mifl. Thefe 
fum^ arc noxious to the lungs, arid fmell like 
burning foot. The muriatic acid is diftinguiOied 
from the vitriolic and nitrous in the. ftrong adhe- 
fioh of its component parts, which is evinced by its 

' not parting with oxygen, andofcourfe its having 
little action on inflammable fubftances. So ftrong 
indeed is the attraftion between the princi- 
ples, whatever they are, which form this acid, 

Tthat they have never been fcparatcd. Its bafe ' 

therefore * 

Chap. 3.] ' Muriatk ^ Acid tf Sea Sab. rj 

therefore is wholly unknown to us, and we have 
DO other evidence than analogy to lead us ta con- 
dude that, like other acids, it contains oxygeiu 
' M. Bcrthollet conjefturcs the radical of the.ipu* 
riatic acid to be of a metallic nature. The muri- 
atic acid is by far the moft abundant of all the acidi 
in the mineral Kingdom ; it is naturally combined 
with lime, magnelia, and natron, or the foflil alkali 5 
with the latter it forms the immenfe beds of f^l 
gem, and the faline matter which gives faltnels tj» 
the ocean* 

As the muriatic acid can only fubfift in the 
gaffeous ftate in the ordinary temperature ' and 
preffurc of the atmofphere, it is neceffary to u9^ 
water in order to cohdenft it. Btsc the ordinary 
muriatic acid is capable of being combined with 
an additional quantity of oxygen, by being diftii- 
Icd with the mineral fubftance called manganefe, 
or with certain preparations of lead and mercury^ 
which readily part with oxygen. The acid rc^ 
fulting from this procefs, and which is called oxy* 
genated muriatic acid, can only, like the former, 
txi& in the gafleous ftate, and is abforbed in a much 
fmallcr quantity by water. When the impregna* 
tion of water by this gas is carried beyond a certain 
poinCt the fuperabundant acid precipitates to the 
bottom of the veflcl in a concrete form. M, 
BerthoUet has fhewn that this acid gas is capable 
of being united with a great number of falifiablc 
bafes } the neutral falts which refult from this union 
arc capable of deflagrating with charcoal, and fomc 
of the imetallic fubftanccs : thefc detonations arc 
6 very 

%6 New Art (jf Bleaching. [Book VI^ 

very violent and dangerous, from the great quan-. 
tity of the matter of heat which die oxygen car- 
ries along with it into the compofidon of the oxy- 
genated muriatic acid* 

The muriatic acid in the oxygenated ftate has 
alfo a remarkable power of rendering vegetable and 
animal matters white. The reducing of this prin- 
ciple to practice has, indeed, been produftive of a 
very eflential improvement in the art of bleaching, 
and for this too we are indebted to M. BerthoUet*. 
By various experiments he was enabled to afcertain 
that the oxygenated or dephlogifticated marine 
acid, as it was at firft called, only differs from the 
common marine acid, in containing a fuperabun- 
dance of oxygen, with which it very readily parts. 
He difcovered further, that oxygen has a rendark- 
able property of dcftroying the colours of vegeta- 
ble matters; that even the dew which falls from the 
atmofphere, and that which comes from the noc- 
turnal tranfpiration of plants, were impregnated 
with oxygen, futficiently to deftroy the colour of 
paper, (lightly tinged with tinfture of turnfole. 
The ancient prejudices concerning the dew of the 
month of May, a feafon when the tranfpiration of 
plants is moft abundant, he conceives to have prigi- ^ 
nated in a fimilar obfervation. 

Attributing, therefore, in his own mind the com* 
mon efFeft of whitening linen in bleach-yards to 
the aftion of oxygen, he was led t% imitate that 
proccfs by applying leys, and the oxygenated mu* 

♦ Annalcs dc Chymie*. 

ChAp. 5.) Neuo Art vf^ledchin^. i*) 

riatic acid alternately^ and by thele means was cna*> 
bled to make linen, &c. petmancntly white, by a 
very quick and eafy procefs. Obfcrving further 
that it was the praftice in common bleaching, to 
marke the linen, &c. in the finifhing, pafs through 
four milk, or a very weak mixture of the vitriolic 
acid with water; he alfo tried the paffing of the 
cloth through a very dilute folution of the vitriolic 
acid, and obferved that it was conlequently cen^ 
dered of a clearer white. * 

The oxygenated acid may be employed either in 
the aerial form, or diluted with water; and the lat- 
ter appears to be the moft convenient mode of ap- 
plying it. ^ The efFedt feems t^refult entirely from 
the aftion of the oxygen which the acid parts with 
to the cloth, and which has a power of deftroying 
vegetable colours. Perhaps the fading of dyed 
(tuffs on being exppfed to the aftion of the light and 
air may be accounted for on the fame principles* 
The acid which M. BerthoUct employed in bleach- 
ing he found had parted with all its fuperabundant 
oxygen to the cloth, and was reduced to the ftate 

. of the common muriatic acid. The foap-leys fecm 
to aft in two ways; by neutralizing any of the fu* 
J)erfluous acid which might be imbibed, it favcs 
the cloth from being corroded ; and it alfo prevents 
the fufFocating fumes of the oxygenated acid from 
being offenfive or injurious. Poflibly the detergent 
quality of the leys may have a further efFeft in car- 
rying off the colouring particles which are detached 

. from the cloth by the aftion of die oxygen. 

Vol. IL C When 

I S sparry Acid. [Book VL 

When ond or two parts of pale concentrated 
nitrous acid are mixed with four of fuming muri- 
atic acid, ari effirrvefcence foon takes place, and 
oxygenated muriatic acid is produced ; at the fame 
time that the mixture becomes of a red colour. 
The mixed acid is called aqua regia^ which has 

- the property of diffolving gold. 

The SPARRY or fluor acid was difcovered by 
Mr. Schcele, and takes its name from the fubftance 
fixrni which it is obtained^ and which is commonly 
known in England under the name of Derbyfliirq 
ipar. This acid when pure afllimes the form of 
gas. In this ftate it is heavier than atmofpheric air, 

^ cxtinguifties fiame,.and deftroys animal life j it has a 
penetrating fmell, iflle that of marine acid, but more 
powerful; and its caufticjty is fuch that it almoft 
inftantly corrodes the (kin* Heat dilates it, iH'ithout , 
producing any other chai^ge. The addition of at-r 
mofpherical air has the effeft of producing with it a 
white vapour, which is more or lefs abundant, in 
proportion as the atmofpherc contains more or le^i 
of humidity. r 

. If vitriolic acid is ptoured on the Derbyftiire fpar, 
which is a' combination of this peculiar acid with 
calcareous earth, and a gentle heat applied, the aciji 
is difcngaged in ad aerial form. It readily 'com- 
bipes with water, a?bd therefore the recipient fhould 

. be half filled wit|i that fluid. The firft experi- 
ments which were made of the diftillation of this 
acid in glafs vefljels, were attended with a ftrikina 
-appearance, which required confiderable acutenels 
for its explanation. It was obferved that as foon 

Chap. 3.] Sparry Acid corrodes Glajs. t$ 

&s the acid gas reached the furface of the water, a 
cjuantity of earthy matter was depofited. This 
Was at firft naturally attributed to the acid carrying 
over with it part of the calcareous ftohe from whicH 
it was diftilled. * Upon examinatioh, ho^^ever, it 
was found that the earth depofited in the water 
Was filiciioils, and this gave rife w an opinion 
that flint was only ^ compofition of this acid witR 
water. This hypothcfis was fooh overturned, by 
obfcrving that the glals veflcl in which the difttUa- 
tion was performed was always corroded, or in part 
diffolved. In this mariner it was found that the flu-^ 
oric acid has the fingular property of diflblving 
glafs. As only a moderate Ifcat is required for 
the diftillation of this acid, it Is now ufual to make 
tfe of l^ad^n veffcls for that purpofe j which arc 
hot Corroded by the acid. The bafe of this acid i$' 
tinknoWn, as we are not acquainted with any (ub^ 
ftincc which can abftrad its oxygen. 

The fluoric acid has been fuccefefully ehnployed 
to make etchings on glafs, in the fame manp<*r as 
nitrous acid is applied to copper. It combines, 
readily with earth and alkalies, but fcarcely, if at 
all, afts on gold, filverj lead, merCury, tin, anti- 
mony, bifmuth, or cobalt, but, it diffolves their 
calces. It afts diredtly op iron and zinc, with the' 
prociuftion of inflammable gas; and it likewife dif- 
folves copper in the metallic ftate, thdugh lefs eafily 
than when Calcined. ' 

If BORAX is diflblvcd to fafturatioh in boiling 

water, and the vitriolic acid added hit fuch quantity 

as to be perceptibly in excefs, a fubftancc will rife 

C a to 

ao Acid of Borax. [Book VI • 

to the furface of the water in the form of white 
icales, which is proved to be a peculiar acid. Many 
chemilb have fuppofed that this acid is an artificial 
produft, formed by a combmation of die falts made 
ufe of in its manufafhire. This opinion, however, 
has now been given up, fmce this acid has been 
found to exift in a ftate of great purity in mineral 
waters^ and fince real bprax may be formed by ad- 
ding this fcaly fait to the mineral alkali. The acid 
of borax requires about fifty times its weight of 
water for its foludon. In a moderate heat it melts 
with k(s intumefcence than borax itfelfi and the 
glaily fubftance, thus formed, is again foluble iq 
water, having only \c&. its water of cryftalliza- 

, The acid of borax is ufed to fufe vitrifiable 
earthsji with which it forms clear and almoft colour- 
leis glafless by the afliftance of heat it diflblves the^ 
earth precipitated from what is called the liquor of 
flints. It unites with ponderous earth, magnefia, 
lime, and alkalis, and forms with thefe fubftances 
ialine compounds. All thefe properties, and more 
elpecially its tafte, the red colour it communicates 
to the tinftures of violets and turnfole, and its neu- 
tral combinadons with alkalies, fufiiciendy indicate 
its acid nature ; but it is the nnoft feeble of all the 
acids, and is difengaged fi-om its . combinations 
even by the carbonic acid. The acid of borax 
is the fubftance called by Homberg fedative faltj» 
from its fuppofed effe£b on the human body. It 
elTervefces with a boiling hot alkaline foludon, but 
not with metals or abibrbent earth$> though it may 
X be 

Chap. 3.] Add of Pbojpbwrus. at 

be united with them. It has a weak attra<5lion for 
inflammable fubftances, particularly fpirits of wine, 
the flame o( which it tinges green. From this^ 
ciroimftance it has been fuppofed^ but without 
fuflicient proof, to contain copper. 

PhosphoiIic acid is obtained by the combuftion 
,of the bones of adult animals, which arc afcerwardd 
pounded, and paflcd through a fine filk lieve ; a 
quantity of dilute vitriolic acid is then poured upon 
the powder, but lefs than is fuflicient for diflblving 
the whole. This acid unites with the calcareous 
earth of the bones, and forms ielenite, and the 
phofphoric acid remains free in the liquor. ^Thc 
liquor is decanted ofl^, and the reflduum wa/hed 
with boiling water ; this water, which has been ufed 
to wafli out the adhering acid, is mixed with what 
was before decanted off, and the whole is gra- 
dually evaporated. The diflblved fclenite now cryf^ 
tallizes in the form of filky threads, which are re- 
moved; and by continuing the evaporation we pro* 
cure the phofphoric acid, under the appearance of 
a white pellucid glafs. When this is powdered, and 
mixed with one third of its weight of charcoal, we 
procure very pure phofphorus by fublimation. The 
phofphoric acid, however, as procured by the 
above procefs, is never fo pure as that obtained by 
oxygenating pure phofphorus, either by combuftion 
or by means of the nitrous acid. 

The phofphoric acid may be rendered concrete 
with very litde difiiciflty, by merely exhaling the 
moifture. It abounds in the animal kingdom, and 
is not unfrequent in the vegetable and mineral. In 

C3 this 

*a Acid of Amber. J^BookVf, 

tUs laft it is found united with lead and iron, as 
well as with calcareous earth. 

The acid of ammr is qbuiped from the fub-r 
jlance of that name> by the fimple application of 
heat. The operation muft not be carried on too far, 
or by too flxong a fire, as the oil of the amber is 
apt to rife with the acid. The acid is found in a 
poncretc form in the neck of the fubliming v? fTcl 5 
it is foluble in twenty-four times its weight of cold 
water, and in a much fmaller quantity of hot water. 
It poffefTes the . qualities of an acid in a very fmal^ 
degree, and only afFcfts the blue vegetable colqujp 
yery fligbtly. 


Chap. 4.] [ 23 3 

Chap. IV. 


7ht Union of an Acid and Alkali dtflrtys the iorrofivi ^aliijf 
of each, '—Neutral Salts do not communicate the faline ^aliij 
to other Bodies, •^'CryfiaUine Torm^^hoiu decomfofeJ. 

N- A T U R A L produftions pafs by grada- 
tions into each other i and I might have gi- 
ven an account of the primitive earths immediately- 
after that of the alkalies, as thcfe fiibftances have 
feveral properties in common, particularly that of 
uniting with acids, and forming neutral compounds. 
Metals alfo are capable of being united with acids, 
and 6f forming with them faline fubftances. A 
lucid order will however be better prefcrved, by 
at prefent confining our attention to the confide- 
ration of luch neutral bodies as arc formed by the 
union of an acid and an alkali. 

To a perfon unacquaint^l with chetpiftryj it is a 
ftriking circumftance that two acrid and corrofive 
fubftances fhould by their union form a compound 
very mild and inaftivc. Such however is the cafe, 
«nd what is ftill more remarkable, their previous 
acrimony, and tendency to combine, renders the 
neutral body proportionably more inoffenfivc. Thus 
an alkali united with vitriolic acid, may be received 
into the body with much lefs caution than when 
f 9mbinnl with the aerial or carbonic acid. The 

C 4 ocutrja 

a+ Neutral Salis. [Book VI. 

neutral falts in general have not fo ftrong a tafte 
'as the fimple, their tendency to combination and 
their folubility being lefs confiderable ; but the cri- 
terion which more efpecially diftinguiihes them 
from the former is, chat they cannot, like the fimple 
falts, communicate the faline properties to other 
bodies. Their cryftalline form Is likewife a cir- 
cumftance which very generally diftinguifties tlic 
neutral from the fimple falts. The volatility of the 
neutral falts is not in general fo great as that of the 
fimple falts. 

Neutral falts may in many calcs be decompofed 
by heat alone, but in general it is neceffary to have 
recourfc to cleftive attraftion, or the addition of a 
third fubftance. When the decompofition is cf- 
feccf ^: by heat alone, the more volatile part is 
forced off: butirfeldom fucceecfs in this way, the 
ingredients adhering fo ftrongly that they rife to- 
gether. It then becomes neceflary to have re- 
courfc to cleftive attraftion. Thus, if from a neu- 
tral fait we wifh to obtain the acid pure, we apply 
another acid which has a greater attradion for the 
alkali. If our objeft is to obtain the alkali fcpa- 
rate, we apply a fubftancc which has a ftronger at- 
traftion for the acid. 


Chap. 5.] .[ ^5 3 

C H A f • V* , 

Glauisr^s Salt ; how dectrnfojei \ Solution of it lefi to cooierjfi- 
taUixes on being foakiu^^^Vitridated Tariar^'^^Vitriolaled Am'^ 

TH E firft fubilances of this kind which chal* 
lenge our attention, arc Glauber's fait and 
vitriolated tartar, or as they are denominated in the 
new chennical nomenclature, fulphat of fuda, and 
fulphat of pot alh. The former of thefe neutral 
(alts is compofed of die vitriolic acid, combined 
with the mineral alkali ; and the latter of the fame 
acid with the vegetabJe alkali. They both have a 
faline bittcrnefs. By heat their ingredients may be 
raifed into vapour^ but no one fimple fait will ic- 
parate them, as no acid has a ftronger attraction 
for the alkali than the vitriolic, nor any alkali a 
ftronger attradtion for the vitriolic acid than the 
fixed Dr. Stahl propofed the cffcfting of this 
feparation as a problem. He knew how to folve 
it, and it was afterwards done by a double eleftivc 
attradUon. Another more curious method is this ; 
take Glauber's fait or vitriolated tartar, melt the 
fajt in a hot crucible, and add to it firft a quan<^ 
tity of charcoal, which has a ftronger attradion for 
the oxygen of the vitriolic acid than the latter has 
|br the alkali* T^efe being expofed tt> heat^ 


l6 Glauber's Salt. [BookVt^ 

the chlrcoal in part difappears, and the mixture 
acquires a derp red colour. If the matter is 
poured out, we find it to be an bepar Julfburis^ 
or liver .of fulphuf, the charcoal having carried 
off with it the oxygen in the form of carbonic 
acid gas. 

Glauber's salt is more fiifiblc than vitriolated 
tartar^ melting in a moderate degree of red heat. 
The folution of Glauber's fait forms into columnarjr 
cryftals, which have generally fix fides, four prin- 
cipal, and two which feem accidental. Its cryftals, 
containing a large quantity of water, are liable to 
have it abftrafted from them by the atmofpherc; 
when they fall to powder, or in chemical language* 
^fflorefce. How much water Glauber's falf is capa- 
ble of containing, is known by its requiring twice its 
weight of water to cryftallize. The water ftiould be 
added in a boiling ftate, and the nnixture boiled a 
little afterwards j it may be fet by in a quiet place, 
and wiltte found cryftallized the next day, or will 
fuddcnly aflbnie that ftate on being ftiaken. On 
cryftallizing, a quantity of heat is perceived to J>c 
emitted by the fubftance 4>a(rmg from a fluid to a 
folid ftat?, and confequently lofing fomc of its 
fetent heat. 

Of Glauber's fait, all that is ufed at pr? lent is 
produced by art. It is faid to be produced by na-. 
turc in the waters of mineral fprings, and of the 
fca. But the fait found in them is ufually not 
Glauber's fait but Epfom fait, confifting of the vi- 
triolic acid and magnefia. Glauber's fait is ob- 
{{lined by uniting th^ vitriolic acid with the mineral 


ttap. 5.] Pitriolated Tartar. ^y 

alkali of (jommon fait, as happens in the proccft for 
obtaining the niuriatic acid. 

ViTRioLAiED TARTAR IS dlftingiiiflied Yrom 
Glauber's fait, by a lefs decree of fufibility. It 
xcqiiircs for its fufion the ftrongcft fire. Its cryllalsf 
are harder, but lefs bright, and do ,not contain fo 
much water as thofe of Glauber's fait. Hence they 
are not liable either to fpontaneous efflofefcencc, 
nor to watry fufion, but, like other falts, which con- 
tain^little water, attraft it ftrongly. This fait de- 
crepMltatcs * in the fire. Vitriolated tartar does not 
appear to be a foffil fait; it is found irt the juices 
of vegetables, and remains in their allies after they 
are burnt. What is ufed in dying and medicine, is 
obtained by art, moft commonly by adding vitriolic 
acid to nitr«4 in order to diflodge the nitrous 
acid. ^ 

One hundred parts of vitriolated tartar contain, 
according to Bergman, about 5a parts of fixed ve- 
getable alkali, 40 of vitriolic acid, and 8 of water 
of cryftallis^lion. 

The vitriolic acid combined with the volatile al- 
kali is. called ammoniacal vitriol, or fulphat of 
ammonia. Ammoniacal falts, it ispfoper to re- 
mark, are fo called from ammotty an Arabic word 
^or fand j or, as Pliny conjcdtires, from the temple 
of Jupiter Ammon, near which animonia ufed to 
be found in great quantities, on account of the ca- 

* In decrepiution the cryjlals l^urft, and fall into powder^ 
from the expanfion of the water which they contain^ by tbft 
Jjeat. This qccaiions that crackling noife which common fait 
flakes when thrown into the fire, 


a.8 Artificial Cold. [Book VTk 

inels dung and urine brought thither. With re* 
fpcft to the general properties of ammoniacal falts^ 
as their alkali is very volatile, they are unable to 
bear any great degree of heat widiout being con- 
verted into vapour> though much more than might 
be expcftcd from their ingredients. They emit pun- 
gent fumes if a fixed alkali or lime is added to 
themj as thefe fubftances, having a ftronger affinity- 
-with the acids, expel the volatile alkali. 

When ammoniacal vitriol is very pure, it has the 
form of needles, which, on careful examination,. are 
found to be flattened prifms of fix fides, two of 
•which are very broad, terminated by fix-fided prifms 
' irregularly formed; but the whole figure of the 
cryftaUization is fubjeft to confiderable varieties. 
This fait is fometimes in the form of quadrangular 
prifms, and is fometimes obtained in very thin 

Its tafte is bitter and urinous i it is light, and 
very friable. It is fcarcely changed by expofure to 
air ; it does not efflorefce like Glauber's fait, but on 
the contrary flighdy attrads the humidity of the 
air. It is very foluble in water, two parts of cold 
or one of hot water being fufficient to hold it in fo-* 
lution; it cryftallizes by cooling; but the mod 
perfedt cryftals are obtained by fpontaneous evapo- 
ration. It likewife unites with ice, which it melts, 
producing at the fame time an excefilve degree of 
cold. It does not ad on the earths, nor on mag- 
riefia; though this laft, according to Bergman, 
feems to decompofe it after a length of time, 


Chap. 5*] jtmmoniacal VitrieL 19 

If mild fixed vegetable alkali^ diat is alkali com- 
bined with the carbonic acid gas, is diftilled with 
ammoniacal vitrioU a double decompofition and 
combination take place. The vitriolic acid unites 
with the fixed vegetable alkali, and forms vitriolated 
tartar. The*carbonic acid gas being at the ifame 
time volatilized, together with the volatile alkal?, 
alfo in a ftate of gas, both unite, and form an am- 
moniacal fait, which cryftallizes in the recipient^ 

Ammoniacal vitriol feems not to exift in a ftate 
.of nature; nor is it ufed either in medicine or the 


Chap. VI. 


Cmmcjt Nitre ; Phenomena attending its Deflagration wth infant* 
maSle Smbftances. '^Natural Hiftory (f Nitre.-^CuSdc Niere^ 
--^nion of nitrous Acid nuith 'various Eartbs.^^Nitrous Am^ 

("COMMON NITRE, or nitrat of pot-afh% 
^ confifts of the vegetable alkali and nitrous 
acid* Nitre was unknown to the ancients \ the fub- 
ftance which they diftinguifhed by that name was a 
foffil alkali, for we are told by Pliny that it was de- 
tergent, and ufed in making glafs. It is uncertain, 
when nitre was difcovered, buc we find it men- 
tioned in the earlieft chemical writers. Nitre melts 
in a very gentle heat, and in a greater degree of hear 
totally evaporates* Cold water diffolves one-fixth 
of its weight ; and hot water about its own weight 
of this fait. Its cryftals are more regular than 
thofe of any other fak (being prifms of fix fides) 
having very little water in their compofition, and 
therefore not liable to fpontaneous evaporation. 
Its mod extraordinaiy property is its deflagration 
with inflammable fubftances, which happens from 
the decompofition of its acid, by which a large 
quantity of oxygenous gas is fet at liberty. To the 
produdion of this air is owing the rapid combuf- 

• Commonly known under the name of falt-petre. 


Ghap. 6*] Deflaffratknof NUre. * 31 

tjon of mixtures of nitre and inflammable fub- 
ftanccs, as evinced in * gunpowder. When nitre 
is melted by itfelf, no particular efFedt takes place ; 
but if charcoal is added to it in its melted ftate, de- 
flagration or detonation takes place. We arc 
therefore not to confider nitre itfelf as an inflamma- 
ble fubftance, but only as affording the pabulum of 
fire. If yre continue to add charctfal, we find that 
the effcd becomes Icfs and lefs, till it entirely 
ceafcs. What remains in the crucible is different 
from nitre, it requires more heat to keep it fluirf, 
and upon examining it we find it a pure vegetable 
fixed^lkali. The charcoal difappears, becaufe it 
is converted into carbonic acid gas by being united 
with oxygen; and the other component part of ni-r 
irous acid, the azote, by being deprived of its oxy- 
gen, is alfo volatilized and difperfed. 

When the deflagration is performed with fulphur 
inftead of charcoal, the confequences are confidera- 
bly different. Like charcoal indeed, when fulphur 
is added in a certain quantity, it will produce v no 
further deflagration j but when fulphur is ufed, the 
-flame is infupporuble to the eye, and tlie appearance 
of inflammation is greater thoagh the noife is lefs. 
If the refiduum is difTolved in water, it will rea- 
dily cryflallize, and is found to be vitriolated tartar. 
The reafon that lefs explofion is produced by ful* 
phur than charcoal is, that the former, when united, 
widi the oxygen of the nitre, becomes fixed 1 
whereas .charcoal united with the fame principle 

* The rcatder will do well to corfult whni haa been faid 
reipedling gunpowder in Book If, 


^1 Natura! Hftory of Nitre. [Book VT- 

is converted into gas» and efcapes with violence. 
The formation of vitriolktcd tartar is owing to the 
produdion of vitriolic acid from the fulphur *and 
the oxygen^ which combines with the fixed vegeta- 
ble alkali. 

The detonation of nitre is a nice tcft of the in- 
flammability of bodies, as there arc many which arc 
found to have this property when added to nitre in 
a ftate of fufion, which exhibit nafigns of it on or* 
dinary occafions. 

Nitre exifts in large quantities in nature, and is 
continually formed in inhabited places; it is found 
in great quantities Upon walls which are ilheltered 
from the rainj and the Bifhop of LlandafFcoUeded 
a confiderable portion from the decayed mortar of 
an old barn. 

There appear to be three principal circumftancci 
that promote its formation; the firft is, the prelencc 
of chalk, or any^othcr calcareous earth,- as appears 
by its being coUefted from walls covered with plal^ 
tcr, or from the ruins of ancient edifices. This fait 
is likewife found pcrfcdlly pure in chalky earths. 
The Due de la Rochcfbucault obtained it, in the 
, proportion of one ounce in the pound, from the 
chalk of Roche Guyon. 

The fccond circumftance neceflary for the pro- 
duaion of this fait, is the putrefaftion, or iponta- 
ncous decompoficion of vegetable and animal mat- 
ters. It is a well known faft, that places which arc 
moif^ened with animal liquids, or contain animal 
matters in a ftate of putrefa£bion> fuch as dunghills, 
(tables, privies, &c. produce much nijtre. This 


Chap. 6.] . Nitre-SeJs. ^ 

conftant ob{*efVatian has been applied to the formi^ 
tion of artificial nitre-beds* Dry ditches are dug 
and covered with fheds open at the fides j thefe are 
filled with animal fubflances, iuch as dung, the ex- 
crements of quadrupeds^ or birds, with the remains 
of vegetables. Thefe matters are from time to? 
time watered, efpccially with water charged with 
animal or vegetable matters capable of putrefaftion,' 
and they are turned up to renew their furfaces fronn 
time to time. When the putrefeftion is in an ad- 
vanced ftage, a fmall portion- of the matter is taken . 
up and lixiviated, to afcertain whether it contains 
nitre; and when it is found fi*giciently charged 
with that fait, the whole is lixiviated. 

The third circumftance, whichy in the opinion of 
fome, is fuppofed to favour the production of flitreyis 
the accefs of airj this is the caufc of the formation of 
the nitre found on walls; and for this reafon it is that 
nitre-beds require to be frequendy turned over, in 
order that the air may touch them in all points. The 
neceflity of the accefs of air is faid to be ftill, more 
evidently ftiewn by the nitre contained m chalk, as 
it is never found below a certain depth. When the 
three circumftances here treated of are united, the 
prbdudlion of falt-petre is very abundant. Nitre-bedff 
ought always to be conftrudtcd on thefe principles. 

The theory of the formation of nitre has not 
been long known; Glauber, and many other che- 
mifts fince his time, fuppofed nitre to exHl ready 
formed in vegetables, from which they imagined it 
to pafs into animal fubftances, and to become dis- 
engaged by putrefaction; but it was foon perceived^ 

VoL^IL' D that 

j4 Natural Hijicry of Nitre. [Book VI. 

that vegetables do not contain a fufficlent quanticjr 
of nitre to account for what is obtained from nitre- 
beds, M. Thouvencl, whofe diflertation on the 
formation of nitre was honoured with the prize of 
the academy> has made many experiments to dif^ 
cover its origin : he found, that the nitrous acid is 
formed by the combination of an elaftic fluid, dif- 
engaged from animal matters in a ftate of putre&c- 
tion, and pure air. He has likewife difcovercd, 
that the nitrous acid, once formed, combines with 
calcareous earth, when any animal matters are made 
\](e of; and that the remains of vegetables are ufeful 
to afford the fixed alkali, which is the bafe of com* 
mon nitre. But M. Thouvenel did not determine 
the nature of the gas, which is difengaged from 
putrefying animal matters. It is to Mr. Cavendifli 
that we are indebted for the proof that it is the famf 
gas, which conftitutes one of the principles of the 
atmofphere, under the name of azote, or phlogiili* 
cated air, or atmofpheric mephitis. His experi* 
jment, wherein the nitrous acid was formed by the 
combination of this gas with vital air, by means of 
the eledtric fpark, has been already mentioned. 

Cubic Nitri, or nitrat of foda, confifts-of tht 
nitrous acid and the fixed mineral alkali. It re- 
fembles common nitre in all its ftriking qualities 4 
-almofl its only difference is the form of its cryftals, 
which is a paralellopiped. The cryftals adhere (b 
ftrongly, that they are fcarcely ever founddiftin A and 
regular^ For the deflagration of cubic nitre, charcoal 
is awft proper; when performed with fulphur, . 
Glauber's &It is produced^ 


Chap. '6.] Cuhic Nitre. 35 

Cubic nitre has not yet been found in nature, but 
IS always produced by art. The Ihorteft method 
is adding nitrous acid to foflil alkali. Its tafte is 
cooling, and rather more bitter than that of com- 
mon nitre. Fire decompofes it , but it decrepi- 
tates, and does not fo ealily melt as common nitre ; 
like that fait, however, it gives out vita! air durin;> its 
decompofition. It Is (lightly dtliquefccnt when cx- 
^fed to air. It is more foluble in cold water than 
the comnhon nitre, two parts of water, at the tem- 
perature of fixty degrees, diflblving one of the fait. 
It is fcarcely more foluble in boiling water, and 
therefore cannot be had in regular cryftals, except 
by flow evaporation. 

Siliceous earth combines with the bafe of this 
ialt, and difengages the nitrous acid; clay likewife 
ieparates the acid, and affords a refidue in the form 
of frit, which is porous and opake when a ftrong 
heat has been applied. Ponderous cartli decompofes 
this fait, and difengages the mineral alkali. Mag- 
nefia and lime do not fenfibly change it. The 
vegetable fixed alkali has a (Ironger afljnity 
with its acid than the mineral. This faft is 
very eafily fhewn. If a heated folution of cubic 
nitre is divided into two parts, and the cauftic ve- 
getable fixed alkali added to one of them, it will 
afford prifmatic cryftals during its cooling; no 
cryftals, however, will be obferved in the other 
pert, becaufe cubic nitre does not cryftallize by 
mere cooling without evaporation. 
• ThcVneutral falts hitherto examined produce no 
cffe£l whoce^r on cubic ilitres if th^fe falts artf 
D 2 diiTolvcd 

j6 Nitrouj AnmonitU. [Book- Vf* 

diflblvcd together in the fame water, they cryftal- 
lize fcparately, and each in its ordinary manner^ 
the nitre and Glauber's fait by cooling; the vitrio- 
lated tartar and cubic nitre by evaporation^ All 
thefe properties fliew, diat cubic lutrc differs from 
common nitre. 

Nitrous Ammoniac, or nitrat of ammoniac, is 
comp6fed of the nitrous acid and volatile alkali. 
It is more foluble and more fufible than the vi- 
triolic ammoniac. When the heat is increafed % 
little above what is ncceffary for its fluidity, it is 
converted into copious vapours. The degree of heat 
neceffary for its fufion is a little above that of boiling 
water ; and if more heat is fuddenly employed, ifr 
has the Angular property of undergoing deflagra- 
tion, though no inflammable fubflancc (hould be 
added to it, and even in a clofe vcflel. This feems xm 
depend on the dccompofition of the volatile aMli. 

M. Berthollet having expofed ammoniacal nitre 
to the aftion of heat in a pncumato-chemical 
and diftilling apparatus, and having obferved the 
phenomena of this operatioa more carefully tharf 
had been done before, remarks, that- it is not a true 
detonation which takes place, but a fudden and 
inftantaneous decompofition, in which part of the 
volatile alkali is entirely deftroyed. The water 
obtained in the receiver contains a fmall part of the 
nitrous acid difengaged in proportion to the quan- 
tity of volatile alkali dccortipofed i and the lat- 
ter gives out plilogifl:icated air or azodc gas* 
The liquid produ6k of this operation being 
weighed^ a greater quantity of water is found than 


Chap* 6.y jfmmoniacal Nitre. 37 

cxiftedin the ammoniacal nitre j and M. BerthoU 
let thinks that this fuperabundant water is formed 
hy the union of the inflammable gas, which is 
one of the principles of the volatile alkali, with 
the vital air of the nitrous acid. The azotic 
gas, or other principle of the volatile alkali, 
which is fix times more in quantity than the inflam- 
tnable gas, i^ difcngaged and colleAcd under the 
veffels of the pneumatic apparatus. 

This fait difTolves readily in water, and jn a very 
large quantity, but it has not fo ftrong an attraftion 
for water as to be deiiquefcent. It may be decom- 
pofed by the vitriolic acid, or either of the fixed 
^ikalis. The nitrous ammoniac is contained in the 
juices of fome plants, but it is ufually prepared 
\yf artificial combination. 

Dj Xhap. 

Chap, VIL 


SaJ Digefti*vus.^^CommoH Salt. — Rock SaU. -^Natural Uifiory ff 
Salt. — Saltnefs cf the Ocean, --•^U/es of common Salt in ths 
j^rts,'-^Sal Ammoniac, '^^Natural Hijiorj of Sal Ammoniac, 

THE combinations of the muriatic acid with 
the alkalis are, ill, Sal Digestivus, or muri-r 
at of pot-alh, which has alfopeen called the febrifuge 
fait of Sylvius, and is a compofition of the vtva-^ 
riacic ^cid with the fixed vegetable alkali. Its taite 
is penetrating and bitter j its cryftals cubical, bu(^ 
almoft always confufed and irregular. In the 
fire it decrepitates, that is, its cryftals fuddenly 
break and fly in pieces by the rarcfadion of the 
water which enters into their compofition. If the 
heat is then continued, and fufficiently ftrong, it 
melts, and is volatilised without decompofition. It 
is not much altered by expofurc to the airj it is 
however flightly deliquefcent. About three part^ 
of cold water are required to hold one part of this 
fait in folution, and hot water does not diflblve a 
greater quantity. 

Clay appears to decompofe this fajt in part, for 
jnarine acid is obtained by diftilling it with the clays 
found in the vicinity of Paris, This operation^, 
however, in fadt aflfords only a fmall quantity of 
gfid^ and land feems to have a ftmilar effeft. Pon- 

Chap. 7.] Sal Dtgejlivus. jj 

derous earth felzcs its acidj and feparates the alkali^ 
according to Bergman. Magnefia and lime do not 
at all change it. The vitriolic and nitrous acids 
difcngage the muriatic acid with cfFcrvefcencc. 
This fait is found in a ftate of nature, but never 
in confiderable quantities j it is found in fea- water, 
and in the water of fait fprings^ and it exifts, though 
rarely, in places where nitre is found j it is like- 
wife met with in the alhcs of vegetables, and in 
animal fluids. It is not employed in the arts, and 
its bitter tafte prevents its being ufed for culinary 
purpofes. In moft of its properties, however, it is 
very fimilar to common fait. 

ad. Common or Marine Salt is compofed of 
the muriatic acid and the mineral fixed alkali, and is 
therefore the muriat oijoda of the new nomencla- 
ture. This felt requires a full red heat for its fu- 
fion ; ibon after this it begins to evaporate in white 
fumes. It has a ftrong attraftion for water, fo as 
to deliquefcc in a moift air. During evaporation, 
the cryftals of this fait form at the top of the 
fblution, contrary to thofe of other fairs, which 
form at the bottom. When the evaporation is 
carried on quickly, it forms into thin irregular 
crufb, and this is the ftate in which we commonly 
have it. When the evaporation is flow, it aflumes 
the cubic form, and the fmalleft cryftals are the 
mbft regular ; but if examined accurately, one of 
their fides will be found a little hollow. The larger 
cryftals have a pyramidal hollow apex> with a 
broad bafc. This is owing to their fuperior fur- 
fiures being dry when floating in the water, while 

D 4 their 

40 Common SdU. [Book Vi^ 

their inferior furfeccs are moiftened. Hence, as all 
dry bodies have a repulfion for water, and as their 
inferior furfaces have a tendency to fink, they are 
hollowed into little pits on the fuperior furfaces. 

This fait contains little water of cryftallizationj 
and decrepitates in the fire. If frequendy diffolvcd, 
evaporated, and dried, its quantity is more dinni- 
niftied than that of any other fait. By decompofi- 
tion we obtain either its acid or it:s alkali. The old 
chemifl:s ufed to obtain its acid by heat alone, but 
this is troubleforne, and requires veflels capable of 
enduring great heat. It is nnoft readily decom* 
pofed by the vitriolic acid, which has the ftrongeft 
attraftiOn for the alkali. The nitrous acid will 
alfo deconnpofe it, but is more liable than the vi* 
triolic acid to come over with the muriatic. 
Some water muft be put into the retort with the 
yitriolic acid, otherwifc the muriatic acid will come 
over in fiimes fo copioufly as to burft the veflels. 
The quantity of the water fhould be about half that 
of die vitriolic acid j one half of which fhould be 
put into the receiver to condenfe the fumes of the 
muriatic acid, and the other half mixed witb' the 
vitriolic to prevent its too Hidden adtion. Glaui- 
ber's fait remains after this operation, and this is 
the ufual way of preparing it. The way to decom-^ 
pofe marine fait, fo as to obtain its alkali, is> firft 
to expel the muriatic acid by means qf the nitrous j 
we thus obtain cubic nitre, which muft be defla-p 
grated to obtain the alkali. A better method, how^ 
ever, is to mix a folution of marine fait with cauftic 
yegetable alkalis by evap<S)-ation muriat of pot-aQi 

Chap. 7.3 Natural lEftory ofcwnmm Sab. 41 

is obtained, and the remaining water contains the 
mineral alkali, pure and difengaged. 

Common fait is the moft ufefijl of falinc bodies; 
for though there are fome which refift putrefadtion 
equally well, there is none which is fo friendly and 
agreeable to the human ftomach. Its agreeable qua<r 
lities are not indeed confined to man i mofl: other ani*» 
mals indicate a great fondnefs for it. The rock felt, 
or fal gem, though only one form of common lalt, 
does not melt fo eafily as the common cryftals. 
The moft remarkable mine of this fait is at Cra- 
cow, in Poland, where there is thought to be fufii-i 
cicAt to fupply the whole world many thoufand 
years. In this mine there are houfes, chapels, and 
ftreets of rock fait, which, when illuminated, affbrd 
a beautiful prolpedt. This fait is alfo obtained 
from fame Iprings. When found in the earth it is 
feldom cryftallized in any regular form; it has 
various degrees of whitenels, and is often found 
coloured ; in this latter ftate it is more particularly 
called fal gem, becaufe it often has the appearance 
and trartfparency of gems. ^ 

The ocean differs in lalmefs in different climates. 
It is falter towards the equator than near the poles. 
This feems to arife from the different quantities of 
water which are evaporated, in proportion to thofe 
which fall in rain. One pound of fea water in the 
Baltic yields about a quarter of an ounce of fait j 
near Holland half an ounce ; and in the Britifli Jfeas 
about two ounces. Boyle has alfo obferved, that 
in places of great depth the water is falteft at the 


j^2 Natural Hi/lory of common Salt. [Book VI* 

In the voyage made towards the north pole in 
1773, it was found, that the lea- water at the Nore 
, contained not quite one thirty -fixth of fait; at the 
back of Yarmouth fands> not quite one thirty-fe- 
corid; o£F Flamborough Head^ rather more than 
one twenty-ninths off Scotland, rather lefs than one 
twenty-ninth; latitude 74% at fca, one twenty- 
ninth ; latitude 78*, rather lefs than one twenty* 
eighth ; latitude 8o% near the ice, not quite one 
thirtieth; latitude 80^% under the ice, not quite one 
twenty-eighth ; latitude 68**. 46, rather more than 
one twenty-eighth; latitude 65, at fea, rather lefs than 
one twenty- eighth. Dr. Hales got only one twenty- 
feventh from water taken up in the Mediterranean^ 
md one twenty-ninth from water taken up at the 
Nore. Dr. Rutty fays, he procured one twenty-fifth 
from water taken up in latitude 65 ; one twenty- 
eighth from water taken up near Dublin ; and one 
thirtieth from water taken up at Dungarvan ; and 
Dr, Lucas, that he obtained one twenty-fifth from 
water taken up near Harwich. From other obfer* 
vations alfo it has appeared, that water from near 
Tcneriff contained about one thirty-fecond of fait, 
and that fome from Saint Jago contained fully one- 
fourth* Further experiments are needed to afcertain 
the faltncfs of the fea in different latitudes with 

The fait commonly ufed for culinary purpofes, 
and known by the name of bay-falt, is obtained 
from the water of the fea by evaporation* This 
evaporation is in fome places performed by the 
heat of the fun, the water being let into (hallow 
trenches, in order to expofe as large a furfacc as 

% poiliblc. 

Chap. 7.] Salt fTcris. 43 

poiEble. This method is praftifcd in the foudicra 
provinces of France, and on a very large fcale near 
Aveiro in Portugal, In the northern provinces, 
Yfhcrc the heat of the fun is not fufficiently great, 
artificial fires are employed. In fome falt-works 
thefe two methods are united; and in England, 
and countries where fait rock is plentiful, that fub- 
ftance is diflblved in fait water, and then evapo* 
rated*. In very cold countries another method 


* * A great quantity of rock iait is ufed at Northivieh* ia 
order to llrengthep their brine fprings, and a much greater 
quantity is fent coaflwife to Liverpool and other places^ 
where it is ufed either for (Irengthening brine fprings or 
fea water ; much of this rock fait was formerly exported to 
Holland, and it is ftill fent to Ireland for the fame purpofeu 
Rock fait, and the yrhite fait which is at Northwich, chiefly 
made from rock lalt, is exported free from the (alt duty ; and 
I was infprmed, that the quantity, which is annually exporU 
ed from Northwich, is fo great, that if it paid the duty, it 
would bring in to government, a fum not much fliort of fonr 
hundred thoufand pounds a -yean *' According to the beft 
accounts [ have been able to procure, the grofs duty on fatt 
made in South firitain, amounts annually to feven hundred 
thoufand pounds («)." The du^y on lalt made at NorChwich 
is about feventy thoufand pounds a year, or a tenth part of 
the whole duiy^^). 

' The Northwich rock fait is never ufed at our tables in iti 
crude flate ; and its application to the pickling or curing 
of flelh or iifh, or preferving any provifions, without its being 
previoufly rehned imp white fait, that' is, without its being 
• diflblved in water, and boiled down into what is called 
white fait, is prohibited under a penalty of 40 s. for every 

{a) Camp. Sur. of Brit. Vol. II. p. 26. 

{&) Since I received this information, an additional dnty 
ciiod, a bu(bel has been laid, in 1780, on ialt. The whole 
duty now amounts to 4/. 2</. a buQiel, the buihel weighing 
56 lb. The makers of fait can afford, in molt places, to fell 
fh^ir f4lt« ej^cloiiTe of dut^, from % d. to |o ^. a bofhelf 


44 Mode of obtaining Sak [Book VL 

is employed to feparate the fait from fea-watcr. 
The water 4s expofed in trenches on the fea-fhpre, 


jnonnd of rock fait fo applied. The pore tranfparent mzffcs, 
however, of rock fait, might, probably, be ufed hj us with onr 
I food, without any fort of danger or inconvenience ; at leafl, 
we know that r<5ck fait is fo afcd, without being refined, 
bQth in Poland and in Spain. In the lall of thefe countries^ 
at Cordova in the province of Catalonia, there is a iblld 
mountain of rock fait, between four and ^wt hundred feet in 
height, and a league ^ti circuit ; its depth below the furface 
of the earth is not known (r). This prodigious ix^ountain of 
£ilt, which has no mixture of other matter with it, is efteemed 
fo fingular an appearance, that it; is thought to militate very 
much again (I the opinion of thofe, who would derive the 
origin ofaU the beds of rock fait, which are found under the 
furface of the earth, from <he evaporation of fait water, left 
in fubtcrraneous caverns, either at the deluge, or upon ibme 
more local commotions of the globe. 

* The quantity of rock fait which may be dUFoIved in a defi- 
nite quantity, fuppofe a pint or i6 avoirdupoife ounces of 
water, is differently ellimateJ by different authors. Boerhaave 
is of opinion that 1 6 ounces of water will not dillblve quite 5 
ounces of rock fait (</); Spielmann thinks that they will dii* 
folve 6\ ounces (^) ; Newmann agrees with Spielmann (/); EUcr 
fays, tlut 7 ounces of fofliie fait may be dillblvcd in 16 ounces 
, of water (^); laftly, Hoffmann affu res us, that 16 ounces of 
water will not didbive above 6 ounces of common ialt (^). J * 

(r) Hill. Nat. de V Efpr.g. p. j^t.Stt an accouct'of fiml^ 
lar mountains of rock fait, in Shaw's Travels, p. 229, and i^ 
Pliny's Hift. Nat. 1. xxxi.'c. 7. 

(//) Qh^m. vol. I. p. 476. 

\e) IniL Chcm. p. 48. 

(/) Newmann's Chem. by Lewis, p. 256. 

{g) Obf. Phy, Chem. L. ii. Ob. xvi. 

{h) Ber. Mem. 1750. 


Chap 7.3 fr(m Srine m cold Countries. 4j 

Vrherc it forms fo thin a ftratum, that the cold of the 
atmofphcrc afts powerfully in congealing it. As 


have tried this matter with diitilfed and with common-water, 
and in various degrees of heat^ and cannot but be of opinion, 
that Hoffmann's experiment approaches neareft to the truch ; I 
never could diflblve ^uiu 6 ounces of rock fait in 16 ounces 
of water. It is not wholly improbable, that diiferent forit 
of rock fait may differ fomewhat with reffpe£! to their folubi- 
lity in water. 

If it be admitted, that 16 ounces of water can diflblve 
6 ounces of fait and no more> then we may be certain, tha< 
no brine fpring, in any part of the world, can yield 6 ouncea 
of fait from a pint of the brine. For brine fprings are, ordi* 
narily, nothing but water in which foffile fait has been dif« 
fcdved; Jbut a pint of the ftrongeft brine cannot contain fo 
muck fait as is contained in a pint of , water, which has been 
iaturated with 6 ounces of fait; for a pint of water, in which 
6 oances of (alt have been diffolved, is increafed a little in 
bulk, it will do more than fill a pint meafure, arid th€ Talc 
left in the furplus will fhew, how muck the fait, contained in a 
pint of the ftrongefl brine, falls ihort of -6 ounces. Or, we 
may confider the matter in the following manner, which 
will, perhaps, be more intelligible ; 16 ounces of water, im« 
pregnated with 6 ounces of (alt, conftitute a faturated brine, 
weighing 92 ounces; if therefore we would kfiow how much 
Call is contained in 16 ounces of fuch brine, by the rule of 
proportion we may argue, that if 22 ounces of brine con- 
tain 6 ounces of fait, 16 ounces of brine will contain ^^^ 
ounces pf ialt. Hence we may infer, that the flronge ft brine 
fprings will not yield much above one quarter of their weight 
of ialt CO- 

' Dr. 

(i) • ■ I Several pits at Korthwich, and at Barton im 
Lana^lhtre, contain no lefs than fix ounces of fait upon fixr 
teen of brine, which is as large a proportion of fait as water 
will diifolve* Niwm* Cbtm. p, 212, Lewis's note. ~ The 


46 Natural Hiftary of Salt. [Book Vl. 

the frozen part confifts of mere water, the fluid 
which remains is confequently more concentratecL 

* The 

<Dr. Leigh» who firft ihewed the manner of refining rock fidt^ 
informs us« that fome of the ftrongeil fprihgs at Northwich, 
gave feven or eight ounces of fait from a quart of brine ; bat 
a quart of brine weighs confiderably more than 32 ounces^ 
the weight of a quart of ^ water ; fo that the Northwich# 
4>ringS9 from this account^ do not yield a quarter of their 
weight. At Middlewich there is faid to be one fait fprin£> 
which is ilronger than the rell> this fpring yields i^fuUfowrtb 
part of fait (^), and hence it is, probably, fully fatnrated* 
We have an account in Kircher's works, of fome famous 
brine fprings in Burgundy, from which we learn, that on« 
hundred pounds weight of the drongefl brine, gave twenty-^ 
five pounds, or juft ont fourth iA its weight of white fait (/)- 

* There arc a great many brine fprings in Chefhire, Wor- 
cefterfhire, StafFordfhire, Hampfhirc, and in other parts of 
Great Britain, fome of which are fufiiciently rich in fait to be 
wrought with profit, others not. From what has been be* 
fore advanced, the reader will readily comprehend that fix* 
teen tons of the ftrongeft brine confift of twelve tons of wa- 
ter, and of four tons of fait ; and that, in order to obtain 
thefe four tons of fait, the twelve tons of water muft be, by 
fome means or other, evaporated, fo as to leave the fait in a 
concrete form. Suppofe there fhould be a brine, which ia 
fixteen tons ihould contain fifteen wOns of water, and only 
one ton of fait; yet it may chance, that fuch a weak brine 
may be wrought with more profit than the ftrongeft; for the 
profit arifing from the boiling of brine into fait, depends at 

author here is fallen, probably, into a little miftake, by con- 
founding a pound of water with a pound of brine ; for if a 
pound or 16 ounces of water will only diflblve 6 ounces of 
felt, a pound of the brine, thus formed, will only hold' 4^^ 
•ances of fait. 

(i) Philof. Tranf. N« 53. 

(^} Kerch. Man, Sob. Tom. U. Cap. XT. 


Chap. 7-] UJe of Salt in the Arts. 47 

The operation is then completed by means of arti^ 

Pure clay has very little adbion on marine fait. 
Ponderous earth decompofes it, but lime and mag« 
nefia produce no effeft. Common fait is ufed to 
vitrify the furface of fbme kinds of pottery. This 
is done by throwing a* certain quantity of it into 
the furnace, where it is volatilize, and applies itielf 
to the furface of the pottery. This is the kind of 
glazing ufed in the making of white Englifh pot-» 
tery. Common fait is alfo ufed in making glafs» 
to render the glafs whiter and clearer. It is alio 
employed as a flux to fiicilitace the precipitation of 

jnadi upon the price of the fael ufed in boiling it« as upon the 
quantity of £Ut which It yields. Thas the Tea water^ which fur* 
rounds thecoafls of Great Britain, is faid to hold feldom more 
than one thirtieth, or lefs than one fiftieth part of common fak; 
bat fuel is fb cheap at NewcafUe,that t^ey can evaporate thirty 
•r forty tons of water, in order to obtain one ton of (alt, and 
yergain as much clear profit as thofe do, who, in countiea 
!efs favourably fituated for fuel^ boU down the ibongeft 

* The advantage refulting from fh-engthening weak brine or 
fea water, by means of rock fait, is \try obvious. Suppofe 
that the fea water at Liverpool, where large quantities of 
lock fait are refined, ^ would yield one ton of fait from forty, 
eight tons of water, then muft a quantity of fuel fufiicient to 
evaporate forty- feven tons of water be ufed in order to ob« 
tain one ton of fait. But if as much rock fait be put into the 
ibrty-eight tons of feawater, as can be diflblved in it, thea 
will the fea water refemble a t>rine fully faturatcd, each fix- 
teen tons of which will give four tons of fait, and the whole 
qliantity yielded by the evaporation of &rty-feven tons of 
water, will be twelve tons of fait.' 

Wat/on* s Chm. EJl vol II. p« 4^ 


4i SalAmmnuic: . XBoofc VT/ 

, metals from the fcorise, and to prevent their calcic 
nation from the contad of the atmofphere. 

3d. Common Sal Ammoniac is the m^rvax of 
ammoniac of the Frcpch chemifts> and confifts of the 
muriatic acid united to the voknle alkali. This 
felt is converted into vapour before it melts, bur 
may be brought into fufion by being combined 
with other fubftances, or even uncombincd, if pro- 
perly confined. When thrown into the fire, it iir- 
creafes the flame> and tinges it with a blue colour, 
clpecially the flame of charcoal. When the air is 
very moift, this fait deliqucfees. It is very re- 
markable for producing a great degree of cold 
when mixed with water. 

If we wi(h to obtain the acid of fil ammoniae^ 
'we may expel it by means of the vitriolic acid, but 
the fumes cannot be condenfed without great dif- 
ficulty^ For obtaining its alkali, the chemifls gene- 
rally employ the vegetable, as it is the cheapeft. The 
quantity of vegetable alkali ufed is generally equal, 
but perhaps ought a litde to exceed, that of the fal 
ammoniac ; the water is in general equal in weight 
toahe alkali, and a volatile alkali fufficiently flrong 
• is obtained^ The produft is different, according to 
the mildnefs or caufticity of the^fixed alkali. When 
a mild fixed alkali is ufed, fo much volatile alkali 
rifes, that Du Hamel and others thought part of 
the fixed alkali was volatilized, and rofe along with 
It. . This however is found to be owing to the car- 
bonic acid, which made part of the weight of tkc 
fixed alkali, being transferred to the volatile aW 


thap. 8,] Mo^ of preparing Sal Ammoniac. 49 

The fal ammoniac ctf commerce is in the form 
of cakes; It is prepared at Cairo from the foot 
of camels dung> which is burned there inftead of 
wood. This foot is put into round bottles a foot 
iand a half in diannieteri terminated by a neck two 
inches high ; each bottle doiitains about forty pounds 
bf this foQt^ ahd affords neirly fix pounds of the 
fait. Thefe vefiels are expofed to the heat of a 
furnace which zBs dn their bottom^ while the 
upper parti being cooler, fuSers the fait to be coiV- 
denfed there. When the operation, which occu- 
pies three days^ is fini(hedi the bottles are broken 
and the fait taken out ; it receives the form of the 
Upper part of the fubliming veflel^ and the cakes 
are therefore ironvex and unequal, with a protu-- 
berance on one fide from the neck of the fublim- 
ing vtffcL 

Pomet has dglbribed a kind of fal ammoniac in 
loaves^ fimyat to thofe of fugar with the point cut 
off, and whifch are imported into France by the 
way of Holland. This kind is made in the Eaft 
Indies. * Sal ammoniac is, bowetreri now made in 
large quantities in Britain* The volatile alkali is 
obtained in an impure liquid ftate from foot, pr 
bones, or any other fubftance which affords it j to 
this the vitriolic acid is added, and the vitriolic 
amftioniac thus produced is decompofcd by com* 
tnon fait, by a double affinity, or eledtive attrac- 
tion ; the vitriolic acid combining with the mi- 
neral alkali, and the marine acid with Aie 
Volatile alkali. The liquor therefore contains 
Glauber^s ialt and fal ammoniac, which are 
feparatcd by cryftallization i and the fal ammo- 

VoL.'IL E niac 

50 Properties of Sal Ammcmac. [Book Vt^ 

niac is fublimed into cakes for Tale. Lord Dun- 
dqnald cxtrafts volatile alkali from pit-coal ; but 
whether it can be afforded cheaper for the general 
purpofes of commerce, than that of the above 
prcccfs, is not, I believe, yet afccrtained.* ' 

The tafte of fal ammoniac is penetrating, acrid, 
and urinous. The form of its cryftals b a hexahe- 
dral pyj-amid. Cubical cryftals arc fometimes, 
though rarely, formed in the middle of the concave 
and hollow parts of the loaves which are prodi/ced 
by fuWimatfoiu 

This fait poffeffes a fingular property, namely, 
a kind of dufbility, fo that it rebounds under the 
hammer,, and may be bended ; a xifcumftance 
which renders it difficult to pulverife k. 

Sal ammoniac is nofi decompofed -by clay, and 
by magnefia very imperfeftly. Lime, and likewife 
ponderous earth, feparate the volatile alkali, cvca 
without the afiiftance of he8t. If fal ammoniac is 
triturated with quick-lime, the ftrong fmell of al- 
kaline gas is immediately perceived. 

♦ Fourcroy's ChemUlry. Note of the Tranflator,- 


Chap. 8i] - [ 51 3 

Chap. VIIL 


Sparry Tartar j^^Sparry SoJa.-^Baraxi its Properties \ ifs VJk 
in the Arts^'-'^Qmhinations of Salts with Metals* 

TH E combinations of the other mineral acids 
with the alkalies, have in general been very 
imperfedly examined, and I ftiali therefore be very 
brief in treating of them. 

The SPARRY TARTAR, or fluat of pot-afh of the 
French chemifts, is compofcd of the acid of (par 
united to the vegetable alkali. It is^ always in a 
.gelatinous form> and has fo flrong an attraction for 
water, that it cannot be cryftallized. According 
to Scheelc, it is acrid, cauftic, and deliquefcent^ 
when dried and melted; he compares it in this ftate 
to the liquor of ilintis. It appears, that the fire 
difengagcs the fparry acid, and that the filiceous 
earth taken up by the acid melts into a foluble 
earth by means of the fixed alkali. This fait has 
not been applied to any ufe. Of the- fparry foda 
ilill lefs is known ; and the fame may be affirmed 
of the fparry ammoniac. 

The combinations of the acid of borax have not 
attrafted much more attention, except the fubfiandc 
from which this acid derives its name. Borax, the 
borat of foda of M. Lavoifier, is compofcd of.a 
peculiar acid united to the mineral alkali, ' The 
E 2 form 

^1 ]^orax. [Book VI. 

form in which it is expoftd to falc is that of cryf- 
tals, very tranfparcnt, and containing a laige pro- 
portion of water. When a fmall quantity of borax 
is heated fo as to diffolve in its own water, it boils 
in a white foam; and when the water is diflipated^ 
the fait is found to have loft much of its weight. 
By incrcafe of heat, it undergoes a proper fufion, 
and aflumes the appearance of glafs ; but is diftin- 
guiihed from that fubftance, by diflblving and 
cryftallizing again. 

Borax may be decompofed by means of the miK 
rlatic acid. It appears furpriiing, but the faft is 
certain, that a quantity of acid of borax, though 
fo weak an acid in its more obvious proper- 
ties, will diflodge, when heat is applied, both the 
nitrous and muriatic acids, and unite itfelf to their 
alkali. The reafon feems to be, that the attraftioh 
ofdiflerentfubftances for the fame body is diffe- 
rent in different degrees of heat. This again is ttK 
be attributed to a double cledive attraftion, in con- 
fequenceof the addition of the matter of heat. Thi: 
coheiioa of the nitrous and muriatic acids to their 
bafe, is fo much weakened by their affinity with 
heat, or in other words, their tendency to aflbmfe 
iRc gafifeouk form, that the attraAion of the boracio 
»cid> which is more fixed, becomes fuperior, and 
difplaces them. 

Borax, as imported from the Eaft Indies, is very 
impure. When purified, it has a very regular 
form. Its cryftals are fix-fided prifms, two of the 
fides being commonly lai-ger than the others, ter- 
ininited by trihedral pyramids* Its cryftalfization 



Chap* 8.] Vfes of Borax. 53 

i8> however^ fubje£): to confiderable varieties. It 
% is ftyptic> and a&s ftxongly on the tongue, and like 

I alkalies it converts the fyrup of violets to a green* 

( Borax> e3q)ofed to the ^r, lofes a fmatl part of its 

; water ofcryftallisation, and flightly efflorefces. It 

J is foluble in twelv^ parts of cold and fix of hot 

J ^ water. Its cryftals may therefore be obtained by 
^ cooling; but the fineft and moft regular are formed 

J by fufiering the cold faturated folutibn to evaporate 

Ipontaneoufly in the ordinary temperature of the 
^ atmofphere. 

Borax is exceedingly ufcful in many manufac- 
tures. It is employed as an excellent flux in the art 
pf glafs-making, as well as in aflays. It is advan- 
tageoufly employed in Ibldering, which it aflifts 
by promoting the fafion of the folder, by foften- 
ing the furfaccs of the n^etals, and by defending 
them from the aftion of the air. 

Very little is known of the combinations of the 
acid of borax with the vegetable and volatile alka- 

The phofphoric acid, and the acid of amber, are 
capable of combination with the alkalies; but the 
reftilts of thefe combinations are fo little known, 
that I Ihall pafs them over in filence, and haften 
to the confideration of the earthy and ftony fub- 

Some faline, earthy, and metallic fubftances, have 

^ ftich a relation to each other, that they arc fepa» 

rated with great difficulty, and adhere after repeated 

folutions and cryflallizations. This circumftancc 

has give^ rife to another divifion of falts, which 

E3 arc 

54 TpipkSabs. [Book VI. 

arc denbmiiiatcd triple. As they do not, howevcis 
appear of fufficient confequcnce to be treated of 
under a feparate (e6tion> I (hall merely enunnerate 
them at the conclufion of the prefent The moft 
remarkable examples of this kind are, mineral aU 
kali with calcareous earth ; common fait with mag-^ 
ncfia ; vitrblated magnefia with iron j alum with 
iron J viriolated copper with iron j vitriolated cop-j 
per widi iron and i^incj vitriolated iron with 
copper; vitriokitcd iron with jinc i vitriolated iron 
with nickelt 


Chap. 9-] I 55 3 

Chap. IX; 


Fi^ve Kinds of Ettrth.-^Definiiion of Earths. ^^Excepf ions, '■^ 
OthiT general Proferties of Earths, ^^^aUareous Eartb*^^ 

IT is now generally agreed among chcmifts and 
mineralogifts, that all the earthy and ftony fub-« 
'fiances whkh compofe the folid parts of this globe^ 
•are ultimately refolvable into five fimple and ori- 
^inial kinds of earth ; namely, lime or calcareous 
earth, magnefia, barytes or ponderous earth, argill 
•or clay, and frfica or flint**. Thefe fubftances 
agree in' the following properties, whicl^ may be 
xroqfidered as the charaftcriftics of all earthy fub- 
(lances. They are nearly inibluble in water, are 
uninflammable, have nor the metallic fplendour, 
^nd their fpecifie gravity, compared with that of 
water, is not -more than five to one. This defini- 
•tion, however, like that offalts, is not fo precife as 
to be beyond die ^-each crf'critioifm^ becaufe there 
arc fome earchs perfetftly foluble in water, though 
i)ut in fmali proportions, and ther« are many in the 
jnternal parts of the earth which afford the ftrongeft 

* It has lately been fuppofed, that there exiil feveral other 
diftind kinds of earth belonging to •particular foflils. This 
^ay vejy probably be the cafe ; but experiments have not y^ 
been fuificiently multiplied to eftablifh the fad. 

£ 4 (cvideace 

56 Calcareous Earib. [Book VI. 

evidence that they have been in a ftate of folution. 
But the definition, though not ftridly accurate, is 
proper in a general fenie. T^ere is great diffe- 
rence of folubility between earths and ifaltSj for a 
few grains of earth are fufiicieat ta faturate * a 
large quantity of water. There are two other rir^ 
iQumftaape^ not included in the definition, which 
make part of the idea of an earthy fubftance; ift^ 
a great degree of fixedneis; adly, adiipofition to 
form a glafly concretion when melted with other 

LimCy properly fo calliKlj is obtained by expels 
^ing the carbonic acid from cakareovis fubftanccs 
by means of heat. Cakarew earth is in a tolcr 
caUy pure ftate in common quick-lime; bjpt if it 
is required pcrfe6Uy fi-ee fi*om foreign admixture, 
it may be obtained by thp fpilowing prqcefsi If 
pounded chalk is feveral times boiled in diftiUed 
water^ the remainder will cqnfift almoft entirely of 
calc^f^pus earth, combined with the carbonic acid. 
If diftiUed vinegar is added to ^he powder thus ob- 
tained, it will fqrni a faline corpbiqation with the 
jime only, to ti^eexclufion of aU extraneous matter^ 
To a folutiofi of this, decanted from the impuii- 
ties, miikl volatile alkali being added, the alkaU will 
finite with the vinc^far, while the calcareous eart^ 
fea^ the carbonic acid of the alkali, and &lls to the 
bottom in the ftate of a pcrfeftly pure chalk. The 
f arbonic acid may be driyea off by heat^ and cd\^ 

f Sec note f, p. ^, 


Chap, f,] Migfn^ 57 

^pareous earth ^ tHys obtained in ib otoft fimpl^ 

Thfendptnre weight of ([juick^Kme to that of 
(kkcd lime is as 1,090 to 1,287. Every' poun4 
ti:aa imfaiiTe &nir ounces four drams and fifty-three 
gnons of water. 

Calcareous eartl^ is foluUe in the nitrous anc} 
inuriaii^ acids^ and forms deliquefeent falts. It is 
|>rec^itated from its folutions by means of vitriolio 
aei4^ with ii^ich it forms a nearly infoluble com* 
poundi caUed felenlc^ (or plaifter of Paris.) Pure 
calcareous earth» or limey is ibluble in a fmall pro- 
portion in watsr^ with which it oontFafts great faeac. 
It is infiiiibk without addition. It attradts die car^ 
iDonic acid from the fixed alkaUes> and by itfdf 
becoming mild rei^der^ them c^uftic^ Its ipecific 
gravity is 2,723. 

Magnefia does not burn into a cauftic fubfiancc 
like quick-lime, though it is dq>rived of its car- 
bonic acid by the application of heat. It is foluble 
in feveral acids^ and forms with the vitriolic the fat 
cadiarticus amanis, or Eplbm fait. When mixed 
with water, it (hews a very fmall degree of heai^ 
but without any efiervefcence. It requires 7,692 
times its weight of water for its folution* It is not 
precipitated from other acids by the vitriolic, a^ 
f:aicareous earth is. Its fpecific gravity is 2,155. 

Barytes is by for the moft ponderous of the 
^rths, ^m which cir^umftance it derives ita 

? Wi* 

5* Ponderous Earth. [Book YXs. 

With vitriolicacid it forms the ponderous fpar, 
which is infoluble in water; and its combinations 
with the nitrous and muriatic- acids are sdfb. not 
very fohible, bu; with the acetous acid (or vineJ- 
gar) it becomes deliquefcent. ^ Combiwd with 
carbonic acid, it is foluble in 1550 times its weight 
of water, when pure in 900 times; >The ipecimens 
of barytes naturally coipbined with. carbonic. acid 
are rare; it fis more commonly found united wh^ 
the vitriolic acid. From this the earth majr be fc- 
paratcd by the following procefs: Pound 4:he pon^ 
derous fpar, :uid mix it with twice its weight of 
fixed alkali { expofe this mixture to a firong red 
heat for about two hours. . The acid quits itke 
earth to unite with the alkali,' 'forming a neutral 
fait, which miay be wafbcd away; . The eanh re- 
mains combined with carbonic acid, which may b^ 
difpelled by heat. The fpcipific gravity of this 
-earth, when pure, is 5,773. 
I ArgiU, or clay^ is foluble in the vitriolic, nitrous^ 
and muriatic acids, and forms alum with the firft q£ 
thefe. If concrete volatile alkali* is added to a 
folution of pure alum, the alkali and \acid'unxtQ'> 
while the clay falls to the bottom, united with only 
a fiTxall quantity of fixed air. The fluid muft be 
^bftraded by dccaotation, and the precipitate wafli- 
cd With diftilled water, and dried. - Pure clay docs 
«ot become cauftic by burning, but is contraftcd 
in fi.zc, and becomes very hard, Tlic fpcciQc gnu 
vity of ;his earth is only 1,669. 

" * The volatile falts in a folid Hate. 


Chap. 9.] Clay. 59 

The principal natural fpecimcns of aigillaceous 
earth ar^ boles, clays, marles, flates, and mica. In 
none of thefc, however, except the flag-ftone, does 
the. argill amount to half the weight of the whole 
ilibftance. Silica abourfds very much in commoo 
clays. .Baked clays conftitute all the varieties of 
bricks, pottery, and porcelain. If baked in a 
ftrong heat, they give:fire with fteel. 

Silica, or flinty is foluble in only one of the acids, 
the flu9ric. In its indurated ftate, it is always 
fufEcicndy hard to fcratch and ftrike fire with fteel. 
After being burnt, it docs not fall to powder as the * 
calcareous earth does. It produces no effcrvefcence 
with acids. It may be diffolvcd by the fixed alkalies, 
both in the dry and wet way. When alkali and 
flint are xxpofcd to the heat of a glafs-houfe furnace, 
if the alkali is only half the weight of the filica, it 
produces a diaplianous and hard glafs, but when 
the alkali is in double or triple the proportion, the 
giafs deliquefces of itfelf, by attrafting the humi- 
dity of the atmoiphere; and forms what is called 
liquor of flints. This earth is perfeftly diflTolved 
in that wonderfiil boiling watcr-^out, above fixty 
f^ct high, at Gcyfer in Iceland, where by cooling 
it forms a hard Gliccous mafs. Pure filiceous earth 
is obtained by fufing* clear quartz with four times 
its weight of fixed alkali, diflfolving the wholejn 
diftilled water, and precipitating the earth by an 
?cid, Its Ipecific gravity is 2,650. 

• Melting by heat. 


^ Ftint. [Book VI. 

M. Bergman has formed perTefk filiceous cryf- 
tisds by diiTolving filiceous earth in the (parry acid» 
md fuSering it to cryilaUtae (lowly. It is probable 
that nature forms them in a long courfe of time 
jrom a iblution or difi\ifidn of this earth in water. 

Though the fimple earths are all infiifible alofie^ 
yet they may readily be fufed by mixture with eacb 
other. The calcareous earth is found to a& as a 
menftruqm in diffolving the odier earths by heatf 
find when it has once aded on any earth, a com- 
pound menftruum is &rmed» which aAs ftill nK>re 
efficacioufly in diflfolving other earths. Hence it is, 
that any three of the fimple earths may be fbfec] 
incoglafs, provided calcareous ^arth is one of the 

Thus far it appeared necefl&ry to prcmift con- 
cerning the general properues of the five fimple 
earths in their feparate ftate; but as their com-. ^ 
binattons are various, and their ufcs in this laft ftate 
very important, it will be proper to treat of each on 
a more ample fcalc than the limits of a finglc chap^ 
tei' would admit, 


Chap. 10.] [6% 3 

Chap. X. 


iand sCryfials,*^Petrifa3hns,--^Parts of Am^als found i0 
Marie, ISc^-^GypJms.^^rMi Vwritti€S.^^Alahaftir.^^FWtoHt 
^Unt,^Mintral Glafs, — SeUuite. — Gypfeout Spar^ — PUiftem 
of Paris', how prepand'^FufibU or Deriyjbire Spar,'^Sfars, 
low formed. — Beautiful Appearances in different Caverns.-^ 
Metallic Comhinations with calcareous Earths 

CALCAREOUS earth is fomctimcs found 
in the form of powder, but more frequently 
in that of a concrete fubftance called chalk, which 
differs with refpeft to the fineneis of its particles 
atid firmnefs of texture. 

1. Chalk confifts of calcareous earth or lime^ 
united with carbonic acid, and an union of the (ame 
principles aifb constitutes limeftone and marble. 
Thefc fubftances only differ from common chalk in 
their degree of purity, or in the manner of their 
aggregation^, admitting of more or lefs polifh. The 
different coloured veins in marble are produced by 
the admixture of other fubftances, (mod conunonly 
iron) unequally diflributed through the ma(s. 

2. Strata of marie alfo contain calcareous earth, 
more or lefs blended with a confiderable propor- 
tion of clay and fand. 

3* Calcareous earth is often found projefling 
into the interftices and crevices of rocks in a cryf-* 


62 Iceland Cryftals. [Book VI. 

tallizcd ftate, and is then called calcareous fpar. 
It is more or lefs tranfparent, and fhirers into flat 
fragnnents of a rhomboidal figure. One variety is 
called Iceland cryftals. They engaged the attention 
of Sir Ifaac Newtonj by their remarkable quality 
of refrafting the rays of light without feparating 
them into colours, fo as to make a line drawn on 
paper appear double, when viewed through them. 
TMc Englilh lead-mines are -full of fpars; their 
Ihapc is in general a. firm column, terminated ac 
each end with a pyramid. Of thefe calcareous 
Ipars there are many varieties. 

4- Calcareous earth appears in the form of ani- 
mal and vegetable fubftances, petrified into ftone 
by being expofed to petrifying waters. Thefe fill 
up the pores of the fubftancc with calcareous earth, 
and incruft them. Hence we may conclude, that 
this earth is foluble in water, and is depofitcd 
in certain circumftances. The quantity of earth, 
however, contained in the water is very fmall, and ' 
therefore the pctrifaftions are formed fiowly, 
Thofc organic bodies which . refift . putrefeddon 
moft, are frequently found petrified, fuch as bones, 
fliells, and, the harder kinds of wood; on the con- 
trarj', the foft parts of animals, which are very 
fubjeft to putrify, are fcarcely ever found petrified. 
Mr. Kirwan remarks, that pctrifaftions are moft 
commonly found in ftrata of marie, chalk, limc- 
ftone, or clay j feldom in fand-ftone, ftill more 
rarely in gypfum, but never in gneifs, granite, 
.bafaltes or fhoerl; they fometimes occur among 
pyrites and ores of irun^ copper, and filver, and 


Chap, icf.] Calcareous' PettifaSlions. ^j 

almofl: always confift of the fpecies of earrh; ftoncj 
or other mineral, which immediately furrounds 
them. Thofe of fhells arc generally found ncareft 
the furface of the earth, thofe of fifti deeper, and 
thole of wood deepeft. A very remarkable cir- 
cumftance is, that petrifadions are found in cli- 
mates where their originals could not have exifted. 
From the gradual and infenfible concretion of this 
kind of matter from dropping waters, are formed 
the large pendulous columns hanging like icicles 
from the roofs. and fides of caves. The mofl re- 
markable are in the. Peak of Derbyfliire. Some- 
times they are found in the arches of old bridges^ 
and arile from the water oozing through and 
carrying particles of lime with it. This earth fb 
conci^eted is called ftaladites, flone-icicles, or 

5. The flielk of all cruftaceous animals, from 
the coarfeft to the pearl which lines the fhell of 
the oyftcr, are all made up of this calcareous carth> 
with a fmall quantity ofanimal gluten. Egg-fliells 
are of the fame nature, and thofe marine bodies 
which, from their hardnels and vegetable appear- 
ance, are called flony plants, fuch as are all the 
^cies of coral, &c. 

Maries, which have been already mentioned as 
containing calcareous earth, are generally divided 
into three kinds. Firft, IheU-marlc; fecond, clay- 
marle; third, ftone-marle. The firft is found in beds 
of confiderable extent, and confifts of thercmains of 
fea.^ (bells ; that which containi the fea 
fl^ells i> commonly ibuQcl .in the greateft (quantity. 

4 . :. -'^: •' : • ': Of 

^4 -WirA- [Book VI. 

Of this kind is that of Paris, nM$ntiohed by M. 
Reaumur, vhich is about ten feet deep^ and of 
g^eat extent, conlifting of oyfter afxl other fca 
Ihells. The i^lics of land ihclls are thofc of 
ihailsi they have probably been carried by the 
current of fomc watci*, and deported at one place^ 
and the water being drained off, the IhcDs remain- 
ed behind. Beds of frclh-water Ihells are alfo 
Ibund* Clay-^marle is a calCareoua matter, which 
when expofcd to the air crumbles to ditft ; it is tci 
be diftinguiflied from common clay, by effervet 
cing with acids, from (he calcareous earth it«con- 
Cains. Stone-n)arIe differs from clay<*marle only in 
being much harder ; but it differs from ordinary (tone 
by breaking to pieces when cxpoled to the air. 

It has been fuppofed by Ibme relpe&able wri* 
ters, that all thefe fpecies of calcareous earth derived 
their origin from fhcUs. Some marbles are evi-^ 
dently formed of Ihdls, and thofe of Derbyshire 
exhibit this appearance in a remarkable manner^ 
Coral is univerfally allowed to be the work of 
fmall animals of the polypus kind* The ftrata of 
lixneftone being alfo found fo frequently united with 
Ihclls and other marine fuhftances, has induced thai 
philofophers to whom I allude to believet that 
the ftone itfclf is altogether compofed of flieU^ 
which at fifft mouldered into pafte^ and were after- 
wards prefed and concreted tc^ether. In one of 
Ac quarries of Italy, the bones of fmall fiflies arc 
'found I 9nd fome rocks in the midland counties of 
Enghnd are almoft wholly compofed of the kind of 
fliells called «ir/ri?rfp#* The animals ^hich produce 
the coral arc here feldom to be founds but in otbe* 


Chap. 10.] Gypjtm or Seleniit. 6^ 

p^rts, as in Jamaica, the bottom of the fea is en- 
tirely covered over with coral, and harbours arc 
Ibmerimes ftopped up with it. Sir Hans Sloanc 
mentions a Spaniih pldte-fhip, which was wrecked, 
and remaned at the bottom of the fea twenty- five 
years, being then* fifhed for, the treafure, as well 
as the timber, &c. were covered with cor^line con- 
cretions. Hence, this coriftant growth at the bot- 
tom of the fea may in time produce beds and ftrata 
of this kind of earth, which, according to circiim- , 
ftances, may be converted into marie, limeftone, 
marble, &d. Calcareous earths, united with car- 
bonic acid, may be known under all forms, by 
effervefcence with the mineral acids. 

6. If vitriolic acid is poured on chalk, the carbo- 
nic acid is expelled, while the vitriolic unites with 
the calcareous earth, and conftitutes a fubftance 
which has very little folubility. This is gypsum, 
felcnite, or plaifter of Paris, which exifts in conli- 
dCrable quantities in nature. Gypfumig are found 
ill folid maffes, very foft, and eafily fcraped with a 
khife. They are diftinguiflied from the combina- 
tions of calcareous earth with carbonic acid, by not 
cficrvefcing with ^cids j and from other earthy 
bodies, by being by heat changed into. a white 
powder, which wheh mixed with a large propor- 
tion of water, fuddenly concretes into a ftony mafs. 
They are moft commonly found in the ftrata of 
clay, fometimes in thofe of fand, under the appear- 
ailce of ^ whitilh coloured mafs, but the fmall pieces 
are tranfparent, and fometimes have a red tinge. 
They arc often compofcd of fmall fhining par- 

VoL^II. F tides. 

66 Alahajitr^ Fibrous Stottffy (^c. [Bopk VI* 

ticks, like the grains of fugar, and when under this 
appearance they arc particularly called gypfuncx, 
\y hen hard, fo a* to admit of being cut into toys 
and figures, they arc called alabaftcr. The fecond 
form under which they are found^ is that o^ a fibrous 
ftrudure of oblique cryftals, which arc pajjallej to 
themfelves, but which crofs the irui(3 ifroip the 
upper to the under furface. In this ftatc they are 
called fibrarias or fibrous (lone by Dr. I;;IiU» Thefe 
differ much in Cze and regularity of cpncretion. 
The third fpecies is compofed of clear tyanlparcnt 
plates like glafs, in clofe contaft with each other, 
but which may be fcparated. They fplit^with a 
knife into fine plates, very flexiblcj though ihcj 
cannot be bent without producing flaws. They are 
called glacies marina, and fome times N^ufcovy 
glafs, but improperly, as that is a different, fub- 

The fourth fpecies is in the form of fepiratc ob- 
long cryftals, which are called felenites ; fome arc 
long and regular, like cryftals of fait. The fifth 
fpecies ,of gypfeous fpar is of a platey texture. 
Gypfcous fpar varies in compaftnefs and tranipa- 
rency, is fometimes white, fometimes reddifli, and 
is mixed with a greater or lefs quantity, of other 
matter: fometimes wp meet in cryftals. 
The ores of metals are often found in this fpan. 

Sixthly, gypfum is often met with in w^tere. 
of fprings in a difTolved ftatcj fpr we find by cxpcr 
rimcnt, that it is foluble in water, thpugh but in 
fmall quantity. When the water is evaporated, it 
is depolited in cryftals very fmall^ and which apr 
4 pqir 

Chap, to.}' Playi& of Paris. 67 

peat* like a white powder; but by the microfcbpc 
arc found to be oblong regular concretions. 
- MargrafF firft fhewed that all thefe fpecies were 
cdrripofed of calcareous earth and vitriolic acid. 
He took a quantity of gypfeous earth in a fubtilc 
powder, and boiled it for fonip time in a folution 
of fixed vegetable alkali; and upon examination, he 
found the calcareous earth at the bottom in an un- 
combined ftate, and in the folution a vitriolated tar- 
tar. He alfo compofed an artificial gypfum of 
calcareous earth and the vitiiolic acid, which had 
all the properties of a natural gypfum. From 
knowing the compofition of thefe fubftances, we 
may Efficiently underftand their properties, parti-^ 
cularly that of being converted by a moderate 
heat into plaifter of Paris. If the purer kinds arc 
reduced to fine powder, and put into an iron veffel> 
by the time the veffei is heated the powder gro^fs 
light, and is thrown into motion like a boiling 
fluid. There are alfo a variety 6f other earthy pow- 
ders, which when moift give the fame appearance 1 
for the vapour rifing up, makes its way through the 
powder, keeps it afloat, and agitates it like a 
liquid in a boiling ftate. This appearance con- 
tinues till moft of the water is evaporated. After 
this the powder becomes heavy, and lies at the bot- 
tom of the veflfel as before heating. It is then pre- 
pared for plaifter of Paris, foi: if a quantity of it is 
put into fo much water as gives it the confiftence 
of cream, it will foon become folid, and ring like 
a veflcl of earthen-ware, or metal. It lofes its 
F 2 tranfparency 

6i Pkifter of Paris. [Book VL 

tranfparency by heat, and becomes white, Tht 
foftcr kmds are beft for the plaifter of Paris. 

The explanation pf all thefc phenomena is not 
diftcult, when we confider the nature of gypfum, 
which being a faline compound, has all the qualities 
of a fait. In its natural (late it is cryftallized in 
confequence of its containing a quantity of water. 
Heat expels the water; which being again added, 
is attrafted by the gypfum, and occafions a cryftal- 

A more violent heat produces very little change, 
as the vitriolic acid adheres very clofely to the 
earth. If thefe fubftances, however, are mixed 
in powder with a quantity of charcoal-duft, the 
whole of the acid may be diffipatcd, and the cal- 
careous earth only left behind, and thus a parti- 
cular phofphorus is formed. In this experiment the 
charcoal attrafts the oxygen of the acid, which 
is by that lofs rendered volatile, < and is difperfed 
in fumes. 

7. Calcareous earth is alfo found faturated with 
muriatic acid in fea-water and in falt-pits. 

8. Calcareous earth, united with the fluoric acid, 
forms the fufible fpar or fluor, which is commonly 
known by the name of Derbyshire spar. The 
texture of this compound i^ either fparry, or irregu- 
larly Ihattered or cracked. It is either tranfparent 
or opake ; and the fpecimens are of a cubic, rhom- 
boidal, polygonal, or irregular figure. The co- 
loured fpa^-s have the property of emitting light 
when laid on a hot iron, or otherwife heated i but 
they k>fc this property by being made red hot. The 


Chap. 10.] Deriyjhire Spar. 69 

green fpars are the mofl: phofphorefcent, but none 
of them exhibit this quality except when well 
warnned. They are fcarcely harder than common 
calcareous fpars, and therefore do not ftrike fire 
with fteel. They do not melt by themfelves; but 
very much promote the fufion of other ftones, par- 
ticularly the calcareous. They do not effcrvefce 
with acids, either before or after being fubmitted to 
the aftion of fire. 

Mr. Whitehurft explains in the following qian- 
ner the formation of fparry and ftala<5titical pro- 
duftions. When water impregnated with the fpar- 
ry acid proceeds (lowly through different ftrata of 
earths and minerals, it becomes charged with a 
variety of thefe fubftances in folution; and as it 
exudes gradually on the furface of caverns and fif- 
fures, the aqueous particles evaporate, and the 
fparry matter cryftallizes in various forms, inclucj- , 
ing in its own fubftance thp heterogenous matters 
with which it is charged. 

If the quantity of water thus impregnated, which 
exudes through the pores of the earth or (lone, 
is not more than will eafily evaporate in the ordi- 
nary heat of the atmofphere, a fparry cruft is form- 
ed. If the quantity of water exuded exceeds the 
quantity evaporated, ftalaftites are produced in on? 
inftance, and tubes in another. 

If a drop pf water hangs from the roof, almoft 
dropping, the aqueous particles evaporate from the 
furface fooner than from its interior parts. A, 
f ryftallization therefore takes place on the furface, 
wjiile the center remains fluid: the water thus de- 

F3 vm^i 

70 sparry Grottoes. [Book VI. 

tained is continually incrcafing, and the tube gra- 
dually extends downwards. By this procefs, tubes 
are frequently fornned of two feet in length, and one 
tenth of an inch in diameter. The appearance of 
caverns ornamented with thefe fplcndid productions 
exceeds that of the moft laboured works of art: 
tranfparent columns, adom?d vith the moft beauti- 
ful and vivid colours, difpofed fometimes in the 
form of a honey-comb, fometimes in a more irre- 
gular arrangement: . mirrors, reflcfting the images 
of objefts, tinged with a light fhadeof the moft de- 
licate colours, ravifh the eye of the beholder. The 
pillars appear of various forms and fizes; fometimes 
arranged like a regular colonnade, and fometinies 
difpofed with all the delightful irregularity of na- 
ture. The ftalaftites hang like icicles from the 
lofty roofs of thefe ftupendous caverns, and are re- 
flcfted back by the polilhed ^nd glittering floors. 
Some of the moft ftriking caverns of this kind are 
thegrotto of Antiparos*, Ppolc's^ Hole, and Peak 
Hole in Derbyfliire. 

9, Calc^eous 

* The following is an accoant of this famous grotto, commu- 
nicated by Magni, an Italian traveller, to the celebrated Kir* 
cher.— * Having been informed (fays he) by the natives of Pa- 
ros> that in the little ifland of Antiparos, which lies about two 
miles from the former, a gigantic ftatue was to be feen at the 
month of a cavern in that place, it was refolved that we (the 
French confol an4 himfelf) ihould pay it a viiit. In parfu- 
ance of this refolotion, after we had landed on the iiland, and 
walked about four miles through the n^idft of beautiful plains* 
find {loping woodlands, we at length came to a little hill, on the; 
^^ pf which yawned a moft horrid cavern* that with its gloom . 


Chap. 10.3 Tungfiein. yi 

9. Calcareous earth is found faturatcd with a par- 
ticular acid, perhaps of the metallic kincl, namely, 

. the 

at firft ftruck us with terror, and almoft reprefled curioiity. 
Recovering the firft Airprife, however, we entered boldly ; and 
had not proceeded above twenty paces» when the fuppofed fta- 
tue of the giani prefented ilfelf to,our view. We quickly per- 
ceived, that what the ignorant natives had been terrified at as 
a giant, was nothing more than a fparry concretion, formed by 
the water dropping from thf roof of the cave, and by degrees 
hardening into a figure that their fears had formed into a mon- 
Her. Incited by this extraordinary appearance, we were in- 
duced to proceed flill farther, in quell of new adventures in 
this fubterranean abode. As we proceeded, new wonders 
offered themfelves; the fpars, formed into trees and fhrubs, 
prefented a kind of petrified grove; fome white, fome green; 
and all receding in due perfpeftive. They ilruck us with the 
more amazement, as we knew, them to be mere productions of 
nature, who, hitherto in folitude, had, in her playful mo- 
ments, drefled the fcene, as if for her own amufement. 

* But we had as yet feen but a few of the wonders of the place;, 
and we were introduced only into the portico of this amazing 
temple* In one corner of this half illuminated recefs, there ap- 
peared an opening of about three feet wide, which feemed to 
iead to a place totally dark, and that one of the natives affured 
us contained nothing more than a refervoir of water. Upon 
this we tried, by throwing down fome ftones, which rumbling 
along the fides of the defcent for fome time, the found feemed ac 
lall quafhed in a bed of water. In order, however, to be more 
certain, we fent ia a Levantine mariner, who, by the promife 
of a good reward, with a flambeaux in his hand, ventured 
into this narrow aperture. After continuing within it for 
about a quarter of an hour, he returned, bringing fome beau- 
tiful pieces ofj white fpar in his hand, which art could neither 
imitate nor equal. Upon being informed by him that the 
place was full of thefe beautiful incruftations, I ventured in 
once more with him, for about fifty paces, anxioufly and cau- 
tioufty defcending by a ileep and dangerous way. Finding, 
F 4 however. 

72 Tungjlein. [Book VI. 

the tungftenic acid. This combination forms the 
TUNGSTEiN of the Swcdcs. This ftone is remarkably 


however, that we cam^ to a precipice which led into a fj^cioas 
amphitheatre, if I may fo call it, dill deeper than any other 
part, we returned, and being provided with a ladder. Ham- 
beaux, and other thing? lo expedite our dcfcent, our whole 
company, man by man, ventured into the faffhe opening, and 
defcending one after another, we at laft faw ouffelves all toge- 
ther in the moft magnificent part of the cavern. 

* Our candies being npw all lighted up, and the whole place 
completely illuminated, never could the eye be prefented with 
a more glittering, or a more magnidcent fcene. The roof all 
hung with folid icicles, tranfparenc as glafs, yet folid as mar- 
ble. The eye could fcarce leach the lofty and noble ceiling; 
the fides were regularly formed with fpars ; and the whole 
prefented the idea of a magnificent theatre, illuminated with 
an immenfe profulion of lights. The floor confifted of folid 
marble; and in feveral places, magnificent columns, thrones, 
altars, and other objects appeared, as if nature had defigned 
to mock the curiofities of art. Our voices, upon fpeaking or 
finging, were redoubled to an allonifhingloudnefs; and upon 
the firing of a gun, the noife and reverberations were almoft 
deafening. In the mjdft of this grand amphitheatre rofe a con- 
cretion of about fiTteen feet high, that, in fome meafure, re« 
fembled an altar; from which, taking the hint, we caufed mafs 
to be celebrated there. The beautiful columns that (hot up 
round the altar, appeared like candleflicks ; and many other 
natural objcdls reprefented the cuftomary ornaments of this 

* Below this fpacious grotto, there feemed another ca* 
vern ; down which I ventured with my former mariner, and 
descended about fifty paces by means of a rope. I at lad ar- 
rived at a fmall fpot of level ground, where the bottom appeared 
different from that of the amphitheatre, being compofed of 
foft clay, yielding to the prefl'ure, and in which I thruft a 
rfick. to about fix feet deep. "In this, however, as above, 
numbers of the mod beautiful cryftals were formed ; one ot 

* ' . ' ' whichj 

Chap. 10.] Swine Stone. 73 

heavy, and refcmblcs fluor fpar in the form of 
its fragments. It becomes yellow in acids, and is 
found united with petroleum (or mineral pitch) in 
the proportion of ninety- five of the former to four 
of the latter. In this ftate it forms the fwine-ftonc, 
which is of a dark colour, and btcomes fetid by 

10. Calcareous earth is alfo found united with 
three of the metals, iron, copper, and lead; of 
each of which there arc fcveral varieties. When 
united with copper, it is called mountain biue; 
when united with calx of copper, it is denominated 
Armenian ftone. Gypfeous earth combined with 
calx of copper, is called turquoife and malachites. 
The pureft malachite, according to Kirwan, con« 
,tains feventy-five parts of copper and twenty-five 
of aerial or carbonic acid; calcareous earth is 
therefore not an eflfential ingredient. It is of a green 
colour, and is fometimes cut and poliihed as 3 

which, particalarly, refembled a table. Upon onr egreiii 
from thi8 amazing cavern, we perceived a Greek infcriptiott 
upon a rock at the mouth, but fo obliterated by time, that we 
could not read it. It feemed to import that one Antipater, in 
the time of Alexander, had come thither; but whether he pe- 
netrated into the depths of the cavern, he doer not think lit to 
inform vp.^^^Kircher de Mund. Sub. 112. 


C 74 3 [Book VI. 

Ghap. XI. 


JdagnifiAf how Qhuuned. — Epfom Salt. — Soap RocL — Track 

Cbalk.^^Strpentine iitone. — Mica — Tali. — Mufcvv^ Gla/s. 

AJheftot. — Mineral Cloth Mountain Leather. — Moumtahs 

FUac^^Momitain Wood. 

TO obtain macnisia, the mother water of nitre, 
or of common fait, is placed in a large veflel, 
and diluted with a confiderablc quantity of common 
water. Fixed alkali diffolved in water is then ad- 
ded, and the mixture juft made to boifc By thisr 
procefs the magnefia falls to the bottom of the vcf- 
fel in the form of a powder, which is purified by 
repeated aflFufions of water, Magnefia, in its niild 
ftate, confifts of forty parts magnefian earth, forty- 
eight Carbonic acid, and twelve water. The cryf. 
talli^sed aerated magnefia contains half its weight of 
carbonic acid, one fourth magnelian earth, and one 
fourth water. 

Magnefia combined with vitriolic acid conftitutes 
Epsom salt, which in many rcfpcfts refembles 
Glauber's lalt j it may be diftinguiftied, however, 
by an eafy experiment; for if a fixed alkali is ad- 
ded to a folution of Epfom (alt, a precipitation is 
produced, which is not a confequence of adding an 


Chap. !!•] S^ap Rod, FnncbCbdk, ^c. yg 

alkali to a folution of Glauber's fait* Even the 
volatile alkali, if mild, is capable of feparating mag* 
nefia from its acid, by means of a double actradion; 
the alkali unites with the vitriolic acid, and part q£ 
the earth falls to the bottom, combined with carbo- 
nic acid. 

Magnefia enters into tlie compofition of Tome 
earthy fubftances ; the ftones ufually treated of 
under this head confid of magnefia united with 
flint i but the latter ufually predominates. Moft of 
' them are foapy to the touch, and fo fofc that they 
may be cut into variods utenfils. — Of thcfe the (oU 
lowing are the moft remarkable: 

1. Steatites, lapis ollaris, or soap rock, is of va- 
rious colours, but chiefly different fhades of green. 
It does not become ductile in water, and js fiifed 
with difficulty. One variety of it is in the form of 
(ix-fided prifms, another is lamellated. 

2. Smcftis, or French chalk, is found pretty 
plentifully in Cornwall. Its colour is either white, 
yellow, or red and white; fome fpeciracns have 
the appearance of Caftile foap. 

3. Serpentine stone is of different fhades of 
green. The ftrufture of this ftone is fibrous, and it 
might therefore be confounded with another earthy 
matter, called afbeftosj if its fibres did not adhere fo. 
clofely together, as to efcape obfervation, when the 
ftone is cut and polifhed. Of the Terpentine ftone there 
are many varieties, and it is found fpotted or ftreaked 
with a great diverfity of colours. What is commonly 
called ferpentine ftone, is a true Upis oiloris; but 


76 Serpentina Stone^ Mca, £sff. [Book VI,. 

•being variegated like the Ikins of feme ferpents. Is 
diftinguiflicd by another name. Great quantities of 
this (tone are found in Italy and Switzerland, where 
it is ofteA worked into the Ihape of dilhes and other 
veffcls. It is harder than fteatites, but not fo hand 
as to give fire with fteel j and ^Icfs fmooth to the 
touch, but is fufceprible of a good polifti ; it looks 
like marble, and is often in thin pieces fennitranfpa- 
rcnt. The greener forts of this ftone have been 
called nephritic; their colour arifes from manga- 
nefe. But the term lapis nephriticus is comjnonly 
applied to jade. 

4. Micaceous earths, or talks^ may be defined 
earthy or ftony bodies, the texture and compo- 
fition of which confifts of thin flexible particles, 
divifible into plates or leaves, haying a fhirjing fur- 
face. Thefe platcs^^ by being expofed to heat, ftpa- 
rate into finaUer ones, but their flexibility is much 
diminiihed. By "a ftrong heat they curl or crumple, 
but it is very difficult to reduce them to .perfeft 
fufion without addition. The plates of mica, when 
of the pureft kind, are tranfparent, and there is one 
variety, the plates of which, from their near refem- 
blance 10 glafs, are called Mufcovy glafs. Micas, 
however, are often tinged with a vafiety of colours, 
or arc more or Icfs opake. Sometimes they have a 
luilre refembling that of metallic fubflances. Some- 
iimes they are in the form of Ihining powder, like 
that which is ufed in bronzing figures. This ap- 
pearance has often impofed upon miners, who have 
fhought they met with gold and filver, whereas 
^ thcrsi 

Chap. II.] Mufc9^ Glajs. 77 

there is never any metal in thcfe fubftanccs but 
iroi). They are found alfo mixed with other ftones, 
as the granite, which frequently contains a great 
quantity of talk. Freeftone alfo contains more or 
lefs ; its horizontal layers have between them a thin 
ftratum of talk where the ftone more eafily feparatcs. 
It is alfo found in fome kinds of flate, which, when 
expofed to the air, moulder into talky powder. The 
tranfparent Mufcovy glafs is ufed for windows, and 
for .thofe lanthorns which are employed in powder 
magazines, as this fubftance is not fo liable to break 
as glafs, and is unaflkikble by fire. The twifted, or 
crumpled mica, which is found at Hardal in Jemp- 
land, is there manufadtured into kettles and other 
veffels, as alfo for hearths of chimnies; and the 
powder which falls in the working may be mixed 
with common fait for the diftillation of the muriatic 
acid The fhining appearance of the micaceous 
earths has obtained them the names of daze, glim- 
mer, or glift. Talk differs from other micas in its 
laminse or filaments being much tenderer and more 
brittle, but bodi have the metallic luftre. 

5. The ASBESTOS, or amianthus, is a foflil agree- 
ing with talk in having a regular,ftru6kure, in being 
flexible, but differing in being compofed of fibres 
inftcad of plates. When long expofed to air, it 
diffolves into a fort of downy matter, which has 
fome degree of toughnefs, but the fibres of which 
connot be unravelled. Cloth and paper Kave been 
made of thi* fubftance, which rcfift the fire. Al- 


7*^ • ^c*«. ■ [fiddkvr: 

b*h)s, however, thoagh unaflaUable by common 
fires, has fubmitted to the power of ftrong bomtng 
mirrors, and has undergone vitriScation. The acnients 
are faid to have manufaflurcd cloths of this foflll, in 
which they wrapped their dead when they burned 
them, that the alhes might be preferved. Several 
modems have fucceeded in making diis clodij the 
chief contrivances which are neceflary are to mix 
the mineral fibres with a large proportion of flax, 
arid to ufe oil freely; thefe matters arc afterwaitls 
confumed by expofing the cloth to a red heat. 
Aithoagh the doth of afbcfios when foiled is reftor- 
ed to its whitenefs by burning,- yec it does lofe 
fome part of its weight, as has been afcertained by 
accurate experiments. The varieties of rfris curiotls 
genus of foffils are mountain leather or corlc; moun- 
tain flax, to which the name of amianthus is parti- 
cularly applied 5 common or unripe afbcflus, and 
mountain wood. Thefe fubftances all confrft 
nearly of the fame component parts,- and differ 
chiefly in colour, folidity, ©r in the form and di- 
reftion of their fibres. Somfe fpecimens of the 
anatanriius are fo light as to float in water. When 
the fibresa«3 parallel, it is called mountain leather j 
when twifted, mountain cork-. 

The mountain -cork or leather contains in the 
hundred: fmm 56 to < 62 parts of filiceous earth, 
from 2a to 26 of mild magnefia, from 7 to 14 of 
mild calearcous earth, 1.- of clay, and" 10.6 of 
w«a; Ti>«fe-a«ml.>a'whheflagbyfuffoir. The 


Chap. ii«] Mountain C^rky ^c. '79 

ipecimens which are of a yellowilh h'own colour 
arc impure, and melt pretty eafily into a black 
flag. There is alfo a fpecies of a light green 
colour, fomewhat more brittle, and contaminated 
ivith iron. This laft is foluble by heat into a 
femitranfparent glafs. 


[ 8o ] [feookVI. 

Chap. XIL 


Barytes a fiarce Mineral ; found in tixfo States^^^Crifiatum.^^ 
Ponderous Spar^^^Caiuk.'^Li'uer Stone, 

BARYTES is but thinly fcattercd in nature. U 
is found in two dates, combined cither with 
the carbonic or vitriolic acids, ift. When united 
with the former acid it refembles alum, but is hard 
and ftriatcd, as if compofed of radiating fibres 
coming from a center. It is fometihfies of a grcen- 
ifh colour i fometimes jagged, when it is called 
crijtaiumy from its refemblance to a cock's comb. 
Thefe prominences arc found accreted to balk of 
the fame fubftance. 

2. Ponderous earth is more frequently united 
with vitriolic acid. Thefe ftones are found of 
various appearances, pale yellow, blackifti, with 
coarfe fcales, or with fine fparkling fcales. They 
are either tranfparent or opake* The tranfparcnt 
PONDEROUS SPAR is ufually in the form of afix-fided 
very flat prifm, ending in a four-fided pyramid; buty 
like all other cryftals, liable to be varied by the cir- 
cumftanccs attending their formation. The opake 
i|)ecimen$^ called cawk. by the miners^ are of a white, 

<:hap. 12.] Uvet-ftone. Si 

grey, or fewn-colour; frequently of ilo tegular fi* 
gure, but often in the peculiar figure of a numbct 
of fmall convex lenfes united together. Thefe va«^ 
rieties arc all remarkably heavy, in general exceed- 
ing four tinnes the weight of water, and by this cir<* 
cumftance the prefenceof barytes may commonly be 
difcovered. The ftones compofed of vitriolic acid 
and baryces may be known by their fmelling like 
liver of fulphur when rubbed. From this property 
they are called lapis bepaticus^ and Ubirftein (liver- 
ftone) by>the Germans, 


I ?a ] [BookVL 

Grap. XIIL 


dneral Account ^f Cloj^t er Jrgtis.^^lum ; /// Comp^tiomj-'^ 
Ifatural Hifiory^f Alum.^^Aaitm of this Subfiance «» abg^ 
Bodies*'^V/es of Alnm in the Arts.^-^Lat Lun^^'-^Porcelaim 
Clay. ^Manner of, making dij'ertnt ifsnds $f Po/tery,*'^tomt 
Warej'-'TeUonu, or peek's Wan.-^China.^-'Lithomarga^''^' 
Terra Lemnia.^-^Bok^^^ZtoliU.'-^Lafis Laxuli^^^Tripolij-^ 
Brick Ciay^—SUfe. 

THE argill, or earth of day, is one ofthofe 
fubftances which abound moft in nature. 
There are immenfe ftrata of clays, and they make a 
part of every rich foil. The idea commonly enter- 
tained of clay, is that of a natural fubftance, the 
pureft kinds of which are firm, and have a fort of 
&tnefs or unftuofity, and which by being rubbed 
by the finger receive a polifh. When dry, they 
imbibe moifture, fo that when applied to the tongue 
it adheres to them. From tiieir attraftion for wa- 
ter, they are always found moift in a natural ftate. 
If more water is added, they form a diiiStilc pafte, 
which, when thoroughly burnt and dried, becomes 
hard, ftony, and impenetrable to water. On the 
;regular contraftion which clay undergoes from the 
application of diflfcrent degrees of heat, depends the 
f onftruftion of a thermometer for meafuring intenfc 


Chap. 13.3 Different Cbara^ers if CUy. 8 J 

degrees of heat, and invientcd byMr. Wedgwbod^i 
As clays when Iwrrought togcdier become impci 
netr^ble* to watet, they are made ufe of to fetaiii 
water in ponds, &c. This is the reafon that "whcii 
catde are allowed to tread a clayey foil in wet 
weather, the plants die that grew there; for the clay 
being previoufly mixed with the Water, and being 
then compreffed by the feet of the cattle, the ground 
is rendered too tough f6r the vegetables to Ipring up 
•through it, efpeciaUy when the clay thus trodden 
together is Afterwards dried by the heat of the fun* 
Clays difler much in confiftency. Somfc melt in thft 
mouth, others are gritty, and get between the teeth. 
They are white, blue, grey, red, yellow, or black* 
Some are much lefs vifcid than others. Some refift 
a very violent heat wirfiout undergoing any change 1 
but moft of them,, in very intenfe heat, melt into i, 
vitrified mafs. Some of them effervefce with acidsj 
others not. All thefe varieties have but one fpeciei 
of earth for their bafis, and are nothing more thaa 
mixtures of ptire clay with heterogetieous fubftances. 
Thus we often find fbata, which contain a lai^e 
mixture of faiidy alnd gritty particles^ All clays 
which are landy, are fo ^m fand, or calcareous 
earth : when mixed with the latter, they effervefce^ 
The variety of their colour depends on an admix- 
ture of iron; though fometimes of inflamniablfe mat-^ 
ter. The day becoming white in the fire> is the 
fureffc fign of its parity. We Cah aftually cxtraft 
' iron from hxoftof theie clays, cfpeciaUy thofe 
^hidi i ufn to 4 rtd cdloui^ which Cdlotiir h always 

£ See vol. i. p.s^6« 

Ga aflumcd 

i4 ''Alu$i. . [BookVf. 

aiiumed by the calces or ruft of iron. When they 
cfFcrvtfce with acic^s, they clafs with mlirles. Clay, 
united with vitriolic acid, forms that comnxxi an4 
well knoiwn fubftance called alum., 

The 2TVTT»?f la of the Greeks, and die alumen of 
the Romans,, was a native fubftance, and differed 
much from the fait of which I am now treating^ 
The varieties mentioned by Diofcorides refer to 
ftaladites, which contained very little if any alum, 
and that completely enveloped by a vitreous mat- 
ter. The defcriptJons of Pliny are ftill more diffi- 
cult to be underftood, as he had not feen the fub- 
ftance which he dcfcribcs, but merely tranfcribed 
from others. The faditious fait which is now called 
alum, was firft difcovered in the eaftern countries, but 
when, where, or by what means, is unknown. On 
account of its fimilar aftringcncy, and its ufe in the 
arts of tanning and dying, the ney fait has retained 
the old name. 

Among the moft early works for the pre|»u-atioQ 
of alum, was that of Roccho, a city of Lycia, now 
called Edeflfa, hence the appellation Roch alum^now 
commonly miftaken for rock alum). In the neigh* 
bourhood of Oonftantinople, and other parts near 
Smyrna, were many alum-works. The Italians 
hired and made ufe of thefe, but about the fifteenth 
.century introduced thp art into their own country. 

Bartholomew Perdix, or Pcrnix, a merchant of 
Genoa, who had often been at Roccho, difcovered 
the matrix of alum in theifland of Ifchia, about the 
year 1459$ ^^ eftablifhed a manu&^pry there; at 
the fame time John dc Caftro made the fame dif- 


Chap, ij-] Natural Hiftorytf Aim. 85 

covcrjr at Tolfa, by means of the ilex aquifoliunij 
which he had alio obferved to grow in the adjacent 
mountains of Turkey; ^d his opijciion was con« 
firmed by the taftc of the ftoncs. The attempts of 
the Genoefe at Viterbium and Volaterre fucceeded 
extremely well ; infomuch that an cdift of Pope 
JPius 11. prohibited the ufe of oriental alum. 

Manufactories were eftablifhed in Spain, Ger- 
many, England, Sweden, &c. in the courfc of 
the fixteench century. 

The proporrion of the principles may be afcer- 
tained in die following manner: the water is ex- 
pelled by a gende heat; the remaining mafs grows 
opake, fwelis) foams, and at length grows quiet, 
fpongy, and friable s the quantity of earthy bafis 
is eafily detcfptiiijed by prccipitajtion with fixed or 
volatile alkali. 

Mr. Pott firft obferved that when clay is mixed 
with vitriolic acid, and boiled a considerable time, the 
folqtion affords alum, diough hfi obtained but little 
in this way. IVlargrafT fpund that the vitriolic 
acid diflblves one half or mor^ of fhe pureft clay ; 
from the folution he obtained much alum, but al- 
ways found it necclTary to add a certain portion of 
alkaline fait before the alum would apppar ; and he 
could never obtain it without adding a greater 
quantity of vitriolic acid than was pepeflkry to 
compote the aluip. The other half, which djd not 
diffolvc, he concludes to be a very fine fand, or an 
earth of the flinty kind. The (horteft way is to 
add a Ihiall quantity of fixed or voladle alkali tp 
ithe foludon, which immediately becomes muddy, 
Gj the 

thd a&ejj. a^t^io^ fooie of xbe fupcr^Mous afid« a. 
powder precipitates, jcpnfifting. of'thf cijjteisoC 

The alumj however, which is emplojrqd in. the 
s^ts^ is not prepared in this >y.ay. Nature pro^cea 
Ijut a very fmalJ quantity of actual almi), aa4 this 
is mixed with hetero§Ciiepp$ mgjttcfs* or. efporcf- 
ccnces, in various formsj upon ores during calcina* 
tion, l?ut rarely occurs cryilallized. la this latter 
ftate, it is reported to be found in. Egypt, Sardinia, 
Spain, Bohemia, and other pUce^ i it is fooi^times 
generated in the aluminous Tchift ofXapland and. 
Weft Gothland, by. j^ fp^ntan^pqs. deconapofition 
of the ore j befides it is found (but rarely) in minei^ 
fprings. Alum is. nioftly pfcf|are4 frpm Qertain fof- 
fils, or o;-es of alum, as they are cabled, Th^fe ores 
are generally found in ftrata, which appear Jike in- 
durated clays, of a daj^I^ black, colpur, an^* his^e a 
lulphureous fmell. \Vhpn e^pgfed to. tb^ air for 
iome ame, they. grpw. hotj fwpil, and crumbte 
down mto aj)9w4cr, e;nit fujphureous funnies, and 
Jbmctimes take fi^e, Sopiie do. not ui^dergo this 
change mcriply from expofure tp the air," but muft. 
be firft burnt Aod wa^d, and. tt)en expoied to the 
aiir a good ^ while Uefore a)um c^n be obtained, 
After^ they haye been crunpbled down in this man- 
ner, t^^e fteep^^d in water i an alkali is thea 
added, and the alum cryftalU^es and fubfides* 

Thefe ores a?e evidently natural mixtures of clay 
and iulphur. By e^pofure tp air, according to the. 
old fyftcm of -chemiftcy,. it. was fuppofed that the 
flay,a(ljtf4. on tli6' fwJphur in iudi a, manner as to 

" make 

Ch&p; Tj.l Prottfs in M^n^ ko^ Alum. ij 

' make re part wiffi its jffilbgiilbif, ^enc6 ffifcy dc- 

^ phincd the produflioh cif heat. This faft, how- 

ever, is now much Bfttcir erplainedi acedrdiVii^ tS 
ths ne^ fjrftem, by fuppofing that the oiygetibtit 
^ gas of the atitiolphcre is decompoledf and #hn§ 

the oxygen is abfojrbcd* by the fulphtir (widi^ WliicU 
' it forms vitriolic acid) the heat is fet at liberty^ andf 

' becomes fcnfible. 

! After a proper qaaniHty of alkali has been adddj 

I to the foludon, it is cryftallizcd in the conriniorf 

f manner, that is by evaporation. The fcryftafs are^ 

' at firft tolerably diftinft, but of rto' confiderable fiaie. 

' A great quantity of tHeiii being heaped ' togethrf 

1 until they undei^go a watery ftifion, tKey unitii'ihttf 

a mafs, which is called roch alum, and in diis fbrih' 
f it is expofed to fale. 

■ Thar accurate arid attentive cbferver, ffiihbp^ 
Watfdn, in his' Chemical Effays, relates, that being" 
one day engaged, in evaporating fomethingof' oflidr 
from a faueer'made of StaiffbMlhife yellow ware; he, 
was furprifed t(J fee a white lubftahcc bubbling ' 
through a crack in the faucer ; uporf tafting it/hc' 
found it to be afalti and, upon further cxAtainadcirt, 
difcoVered that it' was a* plerfeft alum. The firt/ 
he. obfefves, wias a Very hbtone, anditwkiihade* 
of coal cinders j the fatcer was'jplicctf i^ihthfc'bdr of 
the gl'ate', and the alum, he cotifccives, wasfomrtlici 
from the iulphureoxis add bf the 'cindi^rs uniting' iti' 
felf with the clay, which 'enters into 'the cbmpofi-* 
tion' of the yellow wkre. He was informed' that' 
the vapour which, in fome places, efcapes froitt' thi/ 
coal-pits which are otf fire in Staffordlhffc, form«' 

G4- 9ii 

8t Ckmf$JUm ^ Almn. [Bcx>k VI« 

^n alum whenever it meets with an argillaceous 
earth. , This, he remarks^ is conformable to the 
manner of making alum on the Solfatara^ n^ 
Naples, where they place little heaps of argilJa- 
ceoii^ earths or ftones over the crevices from which 
the fi|lphureous vapour iflues, in order that chey 
may colled a grp^ter qiiantlty of alum. 

This fait contains 'much water, hence it tmdcr* 
gofs what chemifts call the w^try fufion ; after this 
there remains a fubftance called burnt alum^ which 
contains the earth and vitriolic acid, with little or 
no water; this, jf the h^t is increafcd, does not 
melt, nor by he^tt alone can we feparate the whole 
of the acid, though fpme of it rifes; but the addic- 
tion of any infl^mable rpatter difpofes it to rife 
in ifumcs, which are very fulphureous. One hun- 
4red parts of cryftallized alum contain thirty-eight 
•of vitriolic s^cid, ^ighteep ^f clay, and forfy-foup 
of water. 

The (enCbl^. qualities of alqm (h^w it (o be tJie 
oppofite to borax, which is compofed of the fixe4 
alkali and a very weak acid % on the contrary, alum 
is the ftrongeit acid, combined with an earth which 
attracts it very weakly; fo fha( the qualities of the aci4 
are very little altered, for if we gpply a foludon of 
alum, to thp infufion of litmus, it changes it to a red,, 
The fblution has alio a ms^nifejl acid)ty,combmcd with 
another tafte which apprpaches tp fiycetnefe. If an 
alkali is added, the earth is immediately prccipitated> 
and this effed is not only produced by the fixeji an4 
yplatile alkalies, but by magnefia and calcareous 
earth. Alum is often obtained from the liquor of 
t}i( compound of iron and vitriolic acidt 


Chap* 13.] Hmhr£s ExferimMf, 89 

The earth of alum will combine in excels to th^ 
{fit when already formed. M- Beaume boiled % 
folution of alum with the earth precipitated 6x>in 
another portion of alum^ by means of fUed 
alkali; die earth was diflblyed with cifervef* 
cencci the filtrated foludon had no longer 
the tafte of alum, but that of a ha;xl water, did 
not redden the tin^re of turafoie^ but converted 
fyrup of voilets to a green. By fpontaneous eva* 
poradon it afforded cryflals, fcaly and foft to thq 
touch like micas M. Baume compares them to 
lelenice. It is not eaiy to compofc alum by adding 
vitriolic acid to this laturated fait, the mixture be* 
coming acid, but not ftyptic* However, after 
fpoiitaneous evaporation for three months, the fb* 
ludon afforded cryilais of alum mixed with fomc 
micaceous fcales, fimilar to thofe afforded by aluni 
laturated with its earth. 

Alum, heated with combuflible matters, forms 
a fubftance which takes fire on expofure to air, and 
is called the pyrophorus of Hombej^. This che* 
mift, who publiflied an account of the pyrophorus^ 
in the year 171 1, made experiments on human 
excrement, for the purpofe of obtaining a colour* 
lefs oil poffefling the property of fixing mercury 
. into fine filver : the inquiry pr6duced many difco- 
yeries 1 the refidue of this animal fubftance, diftil« 
led with alum, took fire on expofure to the air. 
Romberg repeated this experirttent a number of 
times, and always with fucceis. Lemery the 
younger, in the years 17 14 and 17 15, publifhed 
pVQ memoirs^ in which he affirms^ that-pyropho- 


ros may be* made with a great number of veg«aHe 
and animal, fubftances heated wStRalum. But he 
did not fucceedin* hi$ attempts' to form it with fbme 
other vitriolic falts.'^ Thefe two c:hemifts,^bo (bp- 
jRrfbd alum' t6,bc a'cOuibihatiori of^di^ vitriolic acid' 
and'Cafcare'ouS eartl^ imagined tharthe latter being 
converted Into lime atd-aftedthe Humidity of the 
air, and prodaced*'a degree ' of heitluffit lint to let 
firt'tb ttie ful[)hur, iformed' by the vitriolicf acid and 
SflSirnmable fubftanccs; 

* '^Ibm i$ one of 'the moft uftfulTalt? in" the arts* ^ 
liiA'addfed to tall&w to make^candles Hard. Wood 
fufficiehtly fbakedSn aliim^does not* eafily take fire : 
tht'iSmfc'is trucbf pagerimpregnated \^ith it, which 
lor tbat^reafon is very proper, to keep gun-powder,* 
2S it alfo excludes the moiftuje of the air. This 
paper b alfo ufeful in whitening Clver/ and in' 
filvering brafs without heat. " Alum is ufefiil added' 
nlilk' which does not eafily fepai-ate its batter. 

It i§ p^n^ularly 'ufcfulln dying, in preparing the 
matters to be, dyed> for* by cleaning, and opening 
the pores ujpoh'th'c. furface by a gende corrofion^ it 
both renders 'the Tubftaace fit for receiving the 
colouring particles (by which tire alum is generally 
dSccompofed) and at' the* fame tintc nriakcs' the co- 
}6^>r fixed.' it conftifetes the b'afis of crayons^ 
which generalFy confifl: of the earth ofalum, finely 
pfcjwderedand tinged Tor that purpofe,' with different 
colouring matters. . 

The argillaceous foffils are referred to the fcl* 
lowing heads; 

I. Argilla 

i Oap. 13.1 PotterfC^: ^t> 

. L Arcilla AERAi^A^ to wlpch the faociful nasnq. 

; ^ oCkp lunaE has been applied. This was fupjpofedf 
IX) b^ a pahicular fpecies of calcareous earth> till, 

J M. Screber found that it was a combination oC ajgpU, 
with the carbonic acid. ^ It cffervefces with apidsi^ 
and contains a very frnall proportion of calcareous 
earth, and fometimes of gypfunu It is'^generalljr, 
fpund in fmall cakes of the hardnefs of chalky like 
whiqh it marks white. Its colour is fnpw white, and^ 
when examined by the microfcope it is found ta 
confift: of fmall tranlparent cryftals. It cdTervclccSj 
with acids. 

11. Porcelain clay, ar^lla apyra, the ib^.ol^ 
the Chinefe. This is.ver; refr^ftory,- a^ is wiiU 
great difficulty brought into perfedt fufion." Aften 
it h^ been fubmitted to the aAion of heat^ it is.o^ 
a folid texture J and is fohard as to ftrike fire with, 
fteel. It is found of an excellent quali^tyjnj^ai^ 
and likewife in different parts of Europe. . In Swe<«-i 
den it is met with in coal-pits, between. the ftraca^ 
of coal. Common pipe-clay belongs to thisdivi^, 
(ion, and differs from porcelain clay only in being 
lefs pure, which prevents its burning to a gooid^ 

The eflential ingredient in all kbds.of pottery is, 
clay, or argillaceous earthj, becaufe thele earths arc; 
capable of being kneaded, and eafily receivbgaayi 
form, and of acquiring much folidity and hardnefi 
by expofure to fire. Pottery is, in general, covered 
with a glazing, 01; is made to under^ a vitrificadpi^ 
gt the furface^ without which it would be pprviou^ 

5 . » 

9a Art'af Pottery. [Book VI. 

to fluids. Ordinary pottery is glazed with glaft of 
lead mixed with irctallic calces, or with fufible 
liictallic earths. A fine kind of pottery is made of 
white clays, or fuch as whiten in the fire ; the fur- 
ftce of whith is vitrified by throwing into the fur- 
nace, when the ware is fufEciently baked^ fbmc 
common fait and faltpetr«. The Englilh Itone 
ware -is compofed of tobacco-pipe -clay and ground 
flints. The ufe of the flints is to give ftrengrh to 
tShc wure, fo that it may preferve its form during 
tiie baking. In making this ffone^wape great 
pains are. taken to employ only the finer particles of 
the clay and flint. With this view the clay is much 
beaten ip water, by which the finer -parts b^ing 
idoitA with the fluid are fu(pended, while the coarfer 
fink to the bottom of the veflTcL The thick liquid^ 
confilbng of water and the finer.particlcs of the clay^ 
fe farther. purified by pafling \i through hair and 
tewn fievesof diStrtrnt degrees of finencls. After 
this the liquid is mixed, in various proportions for 
dtflferent wares, with another liquor, of about the fame 
dcnfity, and eonfifting of flints calcined, ground, 
and fufpended in wa.ter. The mixture is then dried 
mrz kib, and afterwards, being beaten to a proper 
temper, it becomes fit for being formed at the wheel 
into difties, plates, bowls, &c. When the ware 
lias been expofed tQ heat for about forty-cight 
hours, it is glazed by means of common fait. This 
is thrown Snt% ti.e furnance through holes in the 
upper part of it, and being converted into a thick 
vapour by the heat, is applied to the furfacc of the 
Jicated ware, and caufes \\ to vitfiiy. This curious 


Chap. 13.] Siy^n's JVare^ ' ^S 

method of glazing earthen ware was introduced into 
\ England by two Dutchmen, near a century ago. It 

^ appears to be produced by a combination of die 

' alkali of the Ifalt with the fili^eous earth of the pot- 

tery. The yellow or queen's >yare is made of the 
fame materials as the flint, ware, jbut in different 
^ proportions. The glazing is alfo different ; it is 

i made by mixing together in water> till it becomes as 

> thick as cream, one hundred and twelve pounds of 

S ground white lead, twenty-four pounds of ground 

flint, and flx pounds of ground flint glafs» 
The ware, before it is glazed, is baked in the 
fire, by which it acquires the property of ftrongly 
imbibing moifture; it is then, dipped in this corn* 
! pofition, ahd fuddenly taken out. It is afterwards 

expofed a fecond time to the Are, by which means 
the glaze it has imbibed is melted, and athinglafi^ 
coat is formed upon its furface, which is more or 
lefs yellow, according as a greater or lefs proportion 
of lead has been yfed. Porcelain, or china, is a 
femivitrified earthen ware of an intermediate nature 
between common wares and glals. The firft {pe« 
cimens of this beautiful manufadtgre came from 
China and Japan. Chinefe porcelain is faidto be 
compoied of two ingredients, one of which is a 
hard ftoiie or rock called ptmtje^ which tiicy care- 
fully grind to a very fine powder; and the other, 
called by them kaoUn^ is a white earthy fubftance, 
yhichthey mix intimately with the ground petuntfc. 
Reaumur examined both thefe matters; and havii^ 
expofed them feparately to a violent fire, he difco^ 
vered that the petuntff hadfufqd without addition, 
bat that the kaolin ha<^ given no fignof fufibility^ 


^ Cbbiefe Pcrfdain. [Book Vf; 

from 'which it appeared that the former was of a 
flinty nature, and the latter argillaceous. He after- 
Wards mixed theft mattcrs,and formed cakes <Jf them, 
which, by being baked, were converted into porce- 
hin fimilar to that of China. Macquer thinks 
diat the firft European porcelains were made lA 
Saxony and in France; and afterwards in England, 
Germany, and Italy. Manufaftorics have fince 
feeen cftaliflicd in almoft all the countries of Europe, 
in many of which porcelain is made very little if at 
all inferior to the Chinefe. 

in. Lithomarga, or stone-marrow, when drjp 
feels as flippery as foap, but is not wholly diffu- 
fiHe in water. When mixed with water, k fells in 
pieces, fo as to aflbme the appearance of curds. In 
the fire it melts into a frothy flag. In the mafs it 
brerics into irregular fcaly pieces. This is the ful- 
ler's earth ufcd in the drefling of cloths. To this 
^ecies alfo belongs the terra lemnia ; this is of a 
brownifti colour and ftiinlng texture, and falls to 
picccf^ in water with a crackling noife. The terra 
lemnia is fo called from the ifland of Lcmnos, now 
Statimane, in the -ffigean fea, whence it is procured. 
It is likewife called th6 Turkifti earth, on account 
of its being imprcflcd widi the fcal of the grand 

• IVi Bole is ar fine and dtofc clay of various co- 
lours, containing a large quatitity of iron. It is ndt 
cafily fbkcncd in water when indurated, as the por- 
celftin and common clays, tut either falls to piecis 
• . ih 

.^hap. 13.] • ArpmimMe^'^cr ^ 

in the form of fine grains, or j-epels the water, an4 
canpot be made dudile. In the fire it grows jblack> 
and is then attrafted by the ioadftone. The ibfc 
boles are of various colours, as red, ycHow, green, 
grey, and blueifh grey. The red kind is that ufed 
in medicine, under the name of Armenian bole j 
an indurated kind of which affords the material for 
red pencils* An indurated bole b frequently 
foqnd in coal-pits, between the.feams of coal^ and 
is called coal-flat^. It is met with frequently 
in pieces like nuts of various fizesi which when 
broken exhibit imprefllons of plants, as the nodules 
of copper«ilate from Ilmenaus contain reprefenta*« 
' tions of filh. A fpecie^ of bole is found with icaly 
particl^> the hornblende of the Swedes. It is diftin- 
guifhed from mica, by the fcales being lefs fhining, 
thicker, and reftangulan It is frequendy mixed 
with pyrites i it is of two kinds, black and greeniih* 
The former, when rubbed fine, affords a green 
powder, and is either of a lamellated or granular 
texture. The greenifh kind is of a granular texture, 
or fVriated. 

V. Zeolite is in general of a cryftalline form, 
compofed of imperfeft pyramids turned towards a 
con)mon center. Their form is fometimes globu- 
lar, but feldom prifmatic. The lapis lazuli 
belongs to the zeolites. Thefe fbfTils are harder 
than fluors, but may be fcratched by fteel. The 
liliceous earth predominates much in them. The 
lapis lazuli contains filver and iron, which gives the 
blue colour. Zeolite melts per Je with .^bujjition 
into a white' firothy flag, which in the niomcnt of 


^ tapis Ldzkli^ Rottm Stmti^ i^c. [Book VL 

fuiion affords a phofphoric light. The lapis lazufi 
firft becomes brown when melted, and then pro- 
duces a clear glafs with blue clouds. By icorifica- 
tion with lead; one hundred weight of it has af- 
forded two ounces of filver. 

VI, Tripoli fecms to be of a volcanic origin. 
It is an earth confifting of very fine particles, and 
is known by its quality of rubbing or wearing hard 
bodies, which gives them a polifli. Other fine 
clays, however, have the lame property when a 
little burnt. The tripoli grows fomewhat harder 
in the fire, and is fufed with great difficulty. When 
crude it imbibes water, but is not foluble in it. It 
taftes like dhalk, and is rough or fandy between the 
teeth, though no fand can be feparatcd from it. 
That which has been juft defcribed is of a yellow 
colour, and is fold by druggifts. This kind of 
tripoli has been lately difcovered in Scotland. Ano- 
ther variety, called the rottcn-ftone, is found in 
Derbyftiire. It is in common ufe in England for 
all forts of finer grinding and polilhing, and is alfo 
fometimes ufcd by lapidaries for cutting of ftoncs. 

VII. Common or brick clay is found of va* 
rious colours, as red, pale red, grey, and blue. It ac- 
quires a red colour, more or lefs deep, in the fire, and 
melts pretty eafily into agreenilh glafs. , It confifts 
of a mixture of pure clay, filiceous and martial (or 
iron) earths, containing alfo a fmall quantity of 
vitriolic acid. The clay is alfo found mixed with 

calcareous ^arth, when it conftitutcs.marb. It 



Chap. I j.]) . Slate. 97 

is alfo found in an indurated (late^ eidier pure or 
mixed with inBammable fubftances^ aiid vitriolic 
acidj in which tzit \t forms the ores of alum« 

VIII. Argillaceous foflile ftoncs, toMthich the de- 
nomination of scHisTi properly belongs. The moft 
reiparkable (lones comprehended under this divifipn 
are the bluifh purple fchiftus, or common roof 
flate ; the dark blue fchiftus, or writing flate ; the 
pyritaceous fchiftus ; the bituminous fchiftus ; the 
argillaceous grit, which is alfo called fandrftone, 
and free-ftone; the killasj the flag-ftonci and the 

The method of fplitting the flate, Ufed for the 
roofing of houfes, is the following ; They expofe it 
in blocks to be well wetted and foaked by the rain ; 
when the froft comes Upon it afterwards^ it rarifit s 
the watefj and cracks and opens all the joints of the 
fione^ fo that when the firoft has completed its work 
it lies in loofe flakes or (kivers. Thus tlie elements 
perform with eafe what no manual art could hav^ 
«alily accomplilhed,. 

. Voii.n. H . ^HAy* 

t 9« 1 [Book VI. 

Chap. XIV. 


fgtmtral Jhrangtment of Flinty Sulfiancis,'''^emj,*^I}iaa» md4 < ^ 
Ruhy.^^appbire.^^Tofax.-^EmeraU,^^ Hyacjutb^'^Amabyft. 
-'^armeU''^Tourmalifi,^-^pal,'^C9mf9fiticm mui Fr^ptrties ^ 
precious Stones. ^^-'^uartK^'^Rock Cryftnls^-^FMUsj'^FUmts*, 
•ftbe Pbemmena of tbe Hydropbanms Stonij^^Moon-Stcme.'^ 
' CbaJcedonjf.^-'^nyx.-^Csmtelion.'^S^rdomyx.'^jfgate^^^otm' 
mon Flint.'^^bertj'^and and GraveU'^Jafperj^FeUt Sptr. 
^^Labrador Stone.^-^Scbiri emd fFbetfione^i^^Jrf of makimg 
Clafs. — Prince Rupert^s Drop and PbiUfipbicsd Pbial.^'^n' 
rious Pbenominon, 

THESE earths are chiefly diftinguifhed bj 
their hardnefs» by which they ftrikc fire 
VfVk fteelj and their property of forming good glals 
ivich alkali. They may be divided into> ij Gems^ 
w precious ftones; a/K^artzj 3, Flints; 4, Jaf- 
pers J 5, Feldt-fpars. 

I, Gems. — The diamond is the hardeft of all bo-< 
dies. Its fpecific gravity is 3>445, hence it refrads 
the rays of light very powerfully ; but it poEefles this 
power even in a much greater degree than might 
be fuppofed from its denfity, and hence proceeds 
its fingular brilliancy. The diamond, properly ^q 
Ci^ed, is colourlefss but it alfo reuins this name 
when it is flighdy tinged either with red or yellow. 
It is thcrjefore not the colour of tbe ftooe, but its 
- • .1 ) X htrdnefi 

.Chap. 14-] . fbetHamnd. 09 

hardnefs and luftre> which obtain it thejdenonuna* 
tion of a diamond. . *:m ,l: » 

Diamonds zxt found in the Eaft Indies^ paiticu* 
larly in the kin^oms of Golcondi and Vilapbur : 
they likeWife come. from the Brafilsj but tHefe laid 
appear to be of an inferioroquality, and are known 
in commerce by the narhe of Portuguefe diamonds. 

Diamonds are ufiially found in an ochreous yel* 
low earth, under rocks of grit-ftone and quartz ; 
thiey are likewife found detached, in torrents which 
have carried them from their beds. Diamonds are 
feldofii found ibo ve a certain fize. The (bvereign^ 
' of India referve the largcft, in order that the price 
of this article may not fall. Diamonds have no 
brilliancy when dug out of the earth, but are covered 
with an earthy cruft, which inclofes a fecond cruft, 
of the nature of calcareous fpar, according to iVf. 
Rome de Lifle. Bright diamonds are occafionally 
found in waters. 

Diamonds very often have no regular form, but 
are flat, or worn roiind. Sometimes they are regu- 
larly c^flallized in o£bahedrons, formed by two 
quadrangular pyramids, united at their ba0s; tihey 
are likewife found with twflve, twcnty-foUr, and 
forty-eight faces. 

Diamonds appear to be compoled of laminae, 
laid upon, each odier ; and they are eafily divided, by 
* ftriking them in the direftion of thfefe laminse with 
a good.ftdel inftrumenL There are, however,, 
ibme diamonds which do not appear to be formed 
of diffiiia laminae, butof twilled fibres, likethofe 
of knob in wood, Thefe laft iire exceedingly 
. ^' .'" ' Ha " hard,. 

too f be Ruby ^ Sapphire, 6?r. [Book VI. 

hardy and cannot be wrought; lapidaries call them 
diamonds of nature* 

Diamonds are (hap^d by fiHl cleaving them in 
the direction of their lamells, and then rubbing 
them with other diamonds. They are then po- 
lilhed by an horizontal ftccl wheel, dufted with 
their own powder mixed with olive oiL 

2. The ruby has been confounded with the 
diamond, on account of its hardnefs and luftre^ but 
fome late experiments fhew that it b eflentially 
different. According to Cronftadt, there arc four 
principal kinds of rubies: — i. The ruby of a deep 
colour inclining to purple, a. The fpinell ruby, of 
a ponceau red, that is, of a bright corn-poppy-' 
flower colour. 3. The balafs-ruby, pale red in- 
clining to violet. 4. The rubiccU, of a reddiih 

3^ The fapphirc,.is tranfparent, and of a blue 
colour, and is' faid to be next to the diamond in 
hardnefs. They are fometimcs of a milky appear- 

4. The topaz is chiefly of different (hades of 
yellow, but is fometimes greenifh. When of a, 
fea-grecn colour it is called aqua- marine; when 
more green, the beryl i when yellowifh green, the 

5. Emerald, the chief colour of which is green, 
is the fofteft of the precious ftones, and when 
heated is phofphorefcent like the fiuqrs. 

6. The jacinth or hyacinth, is ofa.finc reddifh 
yellow colour, and fometimes brpwnj they arc 
formed in prifms, pointed at both ends, 


Chap.. 14*] Ameibyfts^Qamets^i^c. loi 

7. The amcthyft is a gem of a violet, colour, or 
great brilliancy, and as hard as the beft kinds of 
rubies and fapphires, from which it only differs in 
its colour. This is called the oriental amethyft, 
^nd is very rare 5 when it approaches to the purple, 
or rofe colour, it is more efteemed than when it 
inclines to the blue. 

The amethyfts called occidental, are of the fame 
nature as rock cryftals, and have the fame grada- 
tions of colour. Cryftals within the geodtrs, or 
hollow agate-b^ls, are very oftep found of an ame- 
thyft colour, and fome arie very fine. 

8. The garnet, when tranfparent and of a fine 
colot)r, is reckoned among the gems; but it varies 
more than any, both with refpeft to it3 form and 
colour, fome being of a deep and dark red, fome 
yellow and purple, and Ibme brown, black- 
ilh, and quite bpake. The regular Ihape qf the. 
garnet is . the dodecagon, with rhomboidal faces, 
and its chief variation is, the double eigKt-(ided 
pyramid, terminating by four faces on each end. 
In general their luftre . is lefs thaa that of other 
gems, as well as their hardnefs, which yields to the 
file, though they fometimes ftrike fire with fleel. 
Their colour proceeds from the iron which they 
contain j and, according to M. de SaulTure, even 
the fineft oriental garnets attraft the magnetic 
needle at a fmall diftance. The Syrian garnet is 
the fineft, and moll efteemed : it is of a fine red, 
inclining to a purple colour, very diaphanous, hm 
Icfe brilliant thain the oriental amethyft. 

9. The tourmalin has lately been brought much 

H 3 into 

I oa ^i tourmalin and Opal. [Bbok VI. 

into notice by its remarkable property of becoming 
clcftrical, in confcquencc of the finiple applicacioa 
of ^hcat. If it is immcrfed in hot water^ in which 
p'roccfs no frjftion can be fuppofcd to happen, 
after it is removed it gives |igps of qontfgry elec- 
tricity at the two oppofite ends of its prifmatic 

The oriental tourmalins are found in the ifland. 
of Ceylon: they are tranfparent, of a dark brown, 
yellow. From Brafil they are for the moft part 
green j but there are alfo fome red, blue, and yel-. 
low. Froqi Tyrol they are obtained of fa dark a 
green, as to appear opake. They are alfo found 
in the mountains of Old Caftile in Spain. 

IQ. The opal is a moft beautiful ftohe, from the 
changeable appearance of its colours by refraction 
and refleftion. There aretwo kinds i one of which> 
the opal of Konnius, appears olive-colourfed by rc- 
fleftion,. and then appears to be opake ; but 
when held againft the light, it is found to be 
iranfparent,* and then appears of a fine red colour. 
The white opal, of a glafs-like complexion, throws 
oiit green, yellow, purple, and bluifli raysj but it is. 
of a rpddilh, or rather flame-colour, when held 
againfl: the light. 

* The precious ftones arc chiefly compofed of the 
argillaceous and filiceous earths; of which the for-, 
liicr predominates. The diamond is alfo thought 
to contain a peculiar earth, of different proper* 
ties from thofe of any of the five earths above de- 


^ Chap. 14.3 Andyfis rf Gems. 103 

< On diflblving the very fubtle powder of the geim 

1 in a double weight of ritriolic acid highly concen*< 
i trated, the refiduum, after evapomqion^ being walhed 
' with warm waterj yields a metallic colouring fub« 
t ftance> and a fmall portion, of lime. The metallic 
K part^ precipitated by what was in the old chemical no* 

mencLature called a phlogifticated alkaline lixiyiumji 
I yields a beautiful f^ruflian blue} hence we conclude 
f that the red colour of the ruby, as well as the blue 
I of the fapphire^ the yellow of the topazj the tawny 
^ of the hyacinth^ and the green of the emeraI4> are 

to be attributed to iron*. 
I Bergman obtained by analyfis, from one hundred 

parts of the following precious ftones : 

Clay. Flint. Lime. Iron. 
' £merald> r- 60 — • 24 — 8 — 6 

Sapphire, — 58 — 35 — 5 — a 
Topaz, — 46—39 — 8 — 6 
Hyacinth, — 40 — 25 — 20 — 13 
Ruby, — 40 — 39 — 9—10 

From the above it may be coUedeid, that the 
gems agree in this relpeft, that they all confifl of 
the fame principles; and that of thefe the argilla- 
ceous earth forms the greatefl part, then the filice- 
bus, next the calcareous, and leaft of all the iron f.^ 
The genis, except the emerald and hyacinth, reifift 
the moft intenfe fire 1 yet we Icnow that thie niby 

* Bergman's Diflerudons^ p. 15^ 
t Chemical Eflays, DiC 15. 

H4 hu 

104 General Pfopertiesrf Gems. [Book VI* 

has been fbftened' in the focus of a burning niir- 
|-or *. 

" Thefe ftoncs all aflume different forms of ciyftaBi- 
zation^ and as this affc6ls the arrangement of their mi- 
nute parts, it doubtlefs is not without effect on their 
tatemal appearance. Their value depends on their 
hftrdnefs and tranfparency. The degrees of hard- 
tiefs are — i. diamond; c,ruby; 3, fapphire; 4, to- 
pax ; 5, hyacinth ; 6, emerald. 
* The garnet differs from all the above, in the fi- 
licebus earth being more prevalent than the argil- 

-\\v Quartz has lefs tranfparency and hardnefs 
than the precious (fenes. The frafturp of quartzofe 
ftones is vitreous, or like glafs, and they ftrikc fire 
with ftecl. Heat xaufes them to lofe th^ii: hardnefs 
and tranfparency, and reduces them to a white 
opakc earth. They are generally cracked through- 
cut, and. break irregularly,, aqd. into ftiarp frag- 
mentst . Meltp d with alkali they give a more folid 
and fixed gjafs than any others of the iiliccous order, 
^hen the^e is no interruption to their natural ac* 
ercjtion, their fubftance alivays cryftallizes into hex- 
agonal prifms, pbinted at one or both ends. Thefe 
occur in clefts, fifTures, and fmall veins in rocks. 
Qjiartzofe ftones very often contain metals. 

No ver/ remarkable fiones belong to this, genus. ^ 
The varieties are Fat quartz, which is very glofly ; 
It is either colouriefs, or is tinged with white, blue, 

• Chemical Effayf, Diff. 15. 


Chap. 14.3 ^rtzy Rock Cryfial, (Si. 105 

or violet. Dry quartz, tranfparcnt, white, of pale 
green. Spairy quartz, pale yellow, or pale blue. 
Cryftallized quartz is cither opake or tranfparent:* 
the tranfparent and dark-brown kind is called 
fmoky-topaz; the yellow, blue, green, and re4t* 
falfe gems; and the colourlefs, rock cryftalsj whcp 
milky, milk- cryftals, and pebbles. Quartz is alio 
found combined with iron and copper; with the 
former it conftitutes a black calx, with' the latter, a 
red calx. 

III. Flints are nnlore uniformly folid, and not 
fo much cracked in the raafs, as quartz; and arc 
more pellucid than jafper. They are better' for* 
making glaft than the jalper, but not & good as 
quartz, and fcem in moft refpefts to be of an inter- 
mediate nature between thefc ftones. Flint often 
ihcws evident marks of having been in a foft and' 
tough ftate, like glue or jellV. 

The fevcral varieties of flints have obtained more 
dlftinft names, from the variety of their colours, than' 
from any real difference in their fubftance; but 
riiefe are ftill proper to be retained, as the only 
names by which jewellers and others are ufed to 
diftinguifh them. 

!• Jade, lapis nephriticus. This ftpne feels 
un^uous to the touch, but is fo hard as to ftrike 
fire with fteel, and is alfo femipellucid. Thefc lat- 
ter circumftances fufficiently denote its flinty nature; 
though its un6tuofity has induced fome mineral - 
fegifts to think that it ought rather to be referred 
to the argillaceous or magnefian orders. It is not 


^ i66 Lapis NepbritUuSy Cat's Eje^ iSc. [Book VI. 

hi^-dcned by the heat of the furnace^ but it melts by 
cKe folar heat^ in the focus of a burning mirror^ into 
aLgreen^glais. That called by the name of cir- 
cvmcifipn-ftone, which comes from the Amazon 
riverj melts more^ eafily by the concentrated rays 
of the fun into a brown opake gla(s. The cplour 
ojElthefe ftones is either milky> or different Ihadcs 
of green. Thofe of a grey, olive, or ycllowilh 
colour, are the vulgar lapis nephriticusi which 
Dfme they have obtained, from a fuppofed property 
of curing nephritic pains, when applied extem^dly to 
the loins. Their femipellucid appearance, haixl- 
iM^is, and Ipecific gravity, are characters by which 
tjlie lapis n^phriticus may be diilinguiihed from other 
(tones. . ^ 

.2. The pt's eye is a very /caiTCC ftone. It is 
opake, ai^ refleds green and yellow rays, in a man^ 
ner fomewhat fimilar to the eye of the animal 
from which its name is derived. It is found in Si- 
beria. . 

' 3* The Hydrophanes, or oculus mundi. The cha- 
ijifter which diftinguifhes this from all other ftoncs 
is its property of becoming tranfparent in confe^ 
quence of being immerfed in water. This happens 
from its imbibing that fluid, as it becomes again 
opake by being dried. 

This circumftance may be illuflrated by a com- 
parifon with fome other natural phenomena,. The 
appearance of clouds ferves to (hew that par- 
ticles of water, copioufly mixed with thofe of air^^ 
prevent the tranfmifiion of light^ and render the 
mafs more or lefs opake^ although the particles of 

C hap* 14.] Hydropbanaus Stone, 1 07 

eachjfeparately taken^ are pellucid. Thecaufeofthis 
is to be fought for in the difference of the refrafting. 
power ; for, by means of that, the rays are turned 
fi^m their original courfe at every particle,., a cfr- 
cumflance which is very injurious tp tfaniparency. 
A common experiment will ftill more clearly clu-* 
cidate this point. The nwft tranfparent/glafs, when' 
reduced to powder, becomes opake,'becaure the air! 
which now occupies the interftices reflefts the light* 
much more copioufly than the particles of glals. But 
upon pouring on water, which dilplaces the air, ani^ 
which differs lefs from the glafs in its refradling" 
power, a certain degree of tranfparency is reftpred* 
On this principle depends the nature of the hyjdrb- 
phanous (lone, which is opak;e when dry, but gra- 
dually acquires tranfparency by lying in' water.' 
This ftone agrees nearly in Ipecific gravity with* 
water, at leaft is not morediftant from itthan^^ls.' 
Ijlts particles are tranfparent, but it is uniformly 
jJerforatcd by invifible foramina, lb. that the air an4 
yater are admitted, but npt readily, \yhen dry/ 
therefore, on account of the great difference of the 
mediums between the particles of the ftone and' 
thofe of the air, it is opake j but whcri the water 
is gradually imbibed, it grows by degrees pelluciij,^ 
beginning at the furface, and proceeding towaixJs'the 
centre. That the hydrophanes abforbs nipifturc' 
and emits air, which is a fluid of much lefs denfity, 
appears from the weight it acquires, and the frnatt 
l^ubbles which cover its furface during the time i? 
is acquiring it transparency. 

4* Moon*! 

io8 Wbiie ytgate. Onyx,, ^c. [Book VI. 

4. Moon-ftpnCj or rainbow-ftonc, reflcAs light 
of pearl and carnadon colours. Irs fr^fhirc h 
fbliated, and its colour pale blue and milkj'. 

5. Chalcedony, or white agate. — This ftonc k 
lifually cut with a convex furface, and receives a good 
polifh. Its degree of hardnefs is intermediate, be- 
tween that of the onyx and the true agate. It is 
(cmitranfparent, and its colour is ulually very fimi- 
lar to that of nnilk diluted with water. 

6. The onyx is the'hardeft of flints. Its udial 
colour is that of die human nails. It is either mark- 
ed with white lines only, or with black ^d \vhitc 
together. Heat deprives it of colour, andj^ if fud- 
dcnly applied, cracks it. 

7. The carnelion dcrivesits name from its relem- 
6lance to the colour of flefh. Tt is either quite red 
or of different fhades of red, with brown and yel- 

8. The fardonyx is a mixaire of the chalcedony 
^d carnelion, fomedmes difpofed in ftrata, and 
Ibmedmes confufedly blended and mixed together. 
Its colours arc therefore a mixture of white and 
red, fomedmes in ftripes, fometimes irregularly 

9. Agate. This name is given to flints that arc 
Variegated with different colours promifcuoufly 
blended together, and they are eftcemed in pro- 
portion to th? mixture and perfcdion of their co- 

10. Common flint or pebble, is in reality of the 
ftme nature with agate, but wandng the beautiful 
jnd various colours of the fubftaiiccs that bear that 


Chap. 14.] Chert J Sandy J offer ^ 6?^. 100 

name. Chalk and white lime-ftonc are ufually the 
matrices of flints, in which they are imbedded in 
the form of nodules, confifting of nuclei involved 
in a cruft. • 

1 1* Chert is lefs hard and tranfparent than che 
common flint. It is not in general found 
in loofe and fingle irregular nodi^les^ but forms 
veins in rocks. Cheats are fdund of a flefh*colour» 
. white, pale yellow, and greenifli, and leem to ble 
of an intermediate nature between the flints and 

Sand and gravel may be confidered as flinty mas- 
ters, torn away from the rocks in which they origi« 
nally exifl:ed, and afterwards worn and fmoothed by 
. the attrition occafionedby the motion of water. Sand 
and gravel, however, confift of all the variety of 
ftony matters which exifted in ^he maflles from 
- which they proceeded, and are therefore found of 
many 9liffcrcnt colours and properties. 

IV. The name. of JASPERS is given to • all tLc 
opakc filiceous fl:ones, which in their texture* rc* 
femblc dried clay. The principal circumftance, 
belides their appearance, which diftinguiflies them 
froni the other filiceous orders, is their more eafily 
mclring in the fire. They in general contain mu<i 
iron. They are very hard, and admit a good polifh; 
and they are variegated with different colours. They 
are feldom ranged in ftrata, but form confidenibk 
; maflTes and veyis in rocks. They are alfo found in 
fmall round maflTes. The principal fpecies of jafpens 
arc die foUowing^thc white, grey, ydfew^ red, 
brown, green, veined, fpottcd, flowered, and green 



I lo Labrador Stone, Cockle^ (ic. [Book VL 

with red points, or blood ftone. Toys, and more 
'cfpecially cups and fauccrs, arc made of jalpcr. 
Many antique fculptur^s are in fton^s of this nature* 

V. Thcmoft common kind of FELOT-sPiiR is 
formed of rhombic laminae, and has therefore ob- 
tained the name of rhombic quartz. It gives fire with 
Heel, whence it has been called Ipathum fcintillans. 
It is harder than the fchifti, and is fufiUe. It is found 
in loofe mafles, two inches long, or mixed with 
iand, clay, &c. or bedded in granite. It is ufed 
in making china at Drefden,. Its colours are white, 
red, brown, pale yellow, or greenifh. 

The Labrador-ftonc is generally claflfed wieh the 
feldt-fpars. It admits of a very fine poliih, and when 
'in that ftate rcflefts a variety of beautiful colours. 
The ftone itfelf is of different Ihades of grey. 

VL Shikl or cockle, of different fhades of green; 
and the various fpecies of whetftones, are alio com- 
monly referred to the filiceous order, though the 
latter are generally in fome meafure compound. 

The ufes of the flinty fubftances are various, and 
have been partly intimated ; but there is one art, in 
which their ufe is too confpicuous to be paffed over 
in iilence. 

The art of making glafs dependson the fufion of 
earthy fubftances, of which the flinty earth is the 
beft, and for that reafon is called vitrifiablci But as 
earths cannot eaflly befufed without mixture, it is ne* 
ceffary to add certain fubftances which may prcH 
mote the vitrification. In the making of oidi« 
nary ghis, of X^ind, br o^her filiceoiis mat- 

Chap. 1 4.] Art (f making Glajs. i x i 

ter> are mixed with about one of fixed alkali. If 
the glals is not required to be tranfparerit, iffll- 
pure alkali, not freed from the a(hes, is employed; 
but in making the finer and moft^tranfparent kinds 
of gla(s» care Is taken to purify both the earfh 
and the alkalL One of the chief points to be oB- 
ferved in the making of glafs is to heat the mix- 
ture gradually, fo that the elaflic fluids may efcapc 
before the materials cohere, as the ingredients arc 
othcrwife apt to be fo fwcUcd by the di^ngagemcnt 
of air as to be loft by flowing over the fides of the 
veflcl in which they are heated. In order to pre- 
vent this, due proportions of land and alkali arc 
mixed together, and expofed, during a confiderai>le 
time, to a red heat, not intenfe enough to melt them. 
By this calcination the inflammable matters, which 
would have impaired the colour of the glafs, arc 
confumed, and the air expelled. This firft mixture 
of the materials of glafs, after being treated in this 
manner, is called the /ri//. 

The due degree of heat is an ellbntial point in 
making of glafs : it ought not only to be very ftrong, 
but alfo maincuned during a long time. In great 
manufaftories the glals is kept fufed during ten or 
twelve hours before it is taken out of the pots. The 
injgredients are thus more completely melted, and 
more thoroughly mixed, and the appearance of 
threads or veins is in fomemeafure prevented, which 
proceed from the diflTerentdenfity of different portions 
of the glafs, and which therefore aft diflPerently on 
theiays of .light. The imperfeftions of glafles are 



At of Glafs-maBng. [Book Vi. 
(enfibly fclc in the conftnidbn of optical in* 

Good glais, althoi^ kept io fudon for a loqg 
tioie in a great heat^ is never perfedly liquid. It 
t$ always ibmewhat thick, and when taken out may 
be drawn into fine threads. The great duftility 
and flexibility of red hot glafs fits it for being 
itduced into any form. In general the glafe is 
taken out of the pots in which it is fiifed by means 
of an iron tube. When a fufficicnt quantity of the 
glals is coUefted at the extremity of the tube, the 
workman begins to blow thro' it, and thus inflates the 
glals. He occafionally rolls it, in order to form it 
into a cylinder, a cone, &c. and if it becomes too cold, 
he heats it by holding jt before the mouth of the fiip- 
nacc. Glafs, in its tough ftate, may be cut with 
ihears, bended with pincers, prcffcd into moulds, and 
wrought, in a variety of methods dependent on thefe 
properties, into the vaft variety of forms which it is 
niade to afTume. Glafs vcffels.. as foon as made, arc 
carried to an oven, in which they are gradually cool- 
ed ; for without this procefs, which is called anneaUni^ 
they would either break in the cooling, or be liable 
afterwards to be broken by the flighted force. 

1 he principal dcfcdts of glafe are colours, veins, 
and bubbles. The colours which generally injure 
the common alkaline glafs are fliades of gr^en, blue, 
and olive. Thefe are moft cffcaually removed by 
the addirioh of a fmali quantity of manganefe. .The 
caufe of the veins has been already explained, and 
that of the bubbles depends on the imperfeft expul- 
fion of air. 


Chap. 14.3 Princi Rupert* s Drcp. it 3 

The addition of calx of lead to glafs renders it 
much more denfe> and lefs liable to be broken. Ar« 
tilicial gems are only the beft kinds of glafs^ coloured 
ivith different metals; but the modes of applying 
the feveral metals to this ufc will be mentioncd.when 
treating of them. 

There are two toys made of unannealed gl|is> 
which^ though commonly ufedfor the amufement of 
children^ exhibit phenomena which juftly intereft 
the curiolity of the philoFopher. When a drop of 
melted glafs is fulFered to fall into water, it aflfumes 
an oval form, with a tail or neck refembling the 
retort of a chemift. This is called Prince Rupert's 
drop, and poflefles the fingular property^ that if 
the fmalleft portion is broken off, the whole drop 
flies into powder with a kind of explofion, and a 
confiderable ihock is communicated to the hand 
that grafps it*. The other is called the philofophical 
^phial, which is a fmall cylindrical veilel of glafs^ 
open at the upper end, and rounded at the bottdm. 
It is generally made of glafs fo thick that it will bear 
a fmart blow againft a hard body without breaking^ 
but if a fmall pebble or piece of flint is let fall into 
it, it immediately cracks and flies in pieces. This 
veflel is formed upon fimilar principles with Prince 
Rupert's drop, it confiflis of glafs fuddenly cooled, 
and, I fuiped, by immerlion in water. 

* Honour is like that glafly bubble. 
That gives philofophers foch trouble ; 
The oae part crack'd, the whole will fly. 
And wits arc crack'd to find out why. 


Vol. IL I Vafious 

114 Philo/opbical Phial, ^c. X^ook VL 

Various explanations have been offered of thcfc 
fafts. The moft generally received is founded on 
the -aflumption that the dimenfions of bodies which 
are fuddenly cooled remain larger than if the cool- 
ing had been more gradual. The dimenfions, 
therefore, of the fmooth external furface of thcfc 
glaflcs, which are fuddenly cooled, are fuppoled to 
be larger than is adapted to the accurate envelope- 
ment of the internal part, which is neceffarily cool- 
ed in a more gradual manner ; if, thei'efore, by a 
crack or rafure, a folution of the continuity takes 
place in the external furface, the fudden a<5l:ion of 
the parts which remained in a (late of tenfion, to 
recover that of perfedl cohcfion, is fuppofed to cfFcfi 
the deftruftion of the mafs. 

This explanation I confefs has not appeareJto me 
fatisfaftory, and I have been inclined to fufpcft that 
the phenomenon arifes either from a quantity of 
air being included in the fiibftance of the glafs, 
which rufties fuddenly out, on the furface which in- 
cludes it being broken) or that by the fudden cool- 
ing the pores of the glafs are fealed up by the fine 
fnrtooth furface, and contain litde or no air, io that 
on the continuity of that furface being interrupted, 
theVir fuddenly rufhing into all the pores of the 
glafs may effect its diflblution. That the whole 
effeft depends on deftroying^the continuity of the 
furface, I havefufficiently proved ; for unlefs the flint 
J or pebble which is let fall into the philofophical phial 

is large and angular enough to fcracch the furface 
of the glafs, it will not break* To afcertain whe- 
ther the fracture of thefe toys depends oi^ "not upon 


Chap» 140 Curious Mineral. tl$ 

the air, a few experiments might be made, on Prince 
Rbpert's drops in a vacuum j when, if it proceeds 
from air included in the drop, the explofion will be 
more violent, or the drop would, perhaps, ipon* 
taneoufly burft ; and if from the contrary. caufe> 
it will not break at all in vacuo. 

I know not whether I am corre<9: in introducing 
in this place a kind of mineral fubftanp e called^i^^:*- 
enjidesy which is mentioned by Mr. Whitejiurft *, as 
I am not even certain that it belongs to the 
filiceous g^nus, but the fimilarity in the phenomena 
which it exhibits to thofe of the Rupert's drop 
and the philofophic phial mufl: be my apology. It 
may be a volcanic production, and may have under- 
gone a fudden cooling, from fomc accidental caufe 
fimilar to. that of the glals of which I have been 

This ftone has the appearance of black marble, 
and breaks where the explofion happens with a 
polilhed furface, not truly plane, but lying in waves. 
It is found in fiflures of lime-ftonc in HayclifF 
and Ladywalh mines at Eyam, and in Oden at 
Caftleton, in Derbyfhire. It is divided into ,two 
equal parts or flabs, by a line parallel to the fides of 
the fiffure, and thefe flabs are joined by two polilhed 
faces, which feem to be in perfefl: contadt without 
any cohefion. The furfaces are coloured with lead 
©re, or a fubftance very much refembling it, but as 
thin as a covering from a black lead pencil; If 
a fliarp-pointed tool, which the workmen call a 

* Obfcrvations on the Strata in Dcrbylhirc, p. 185, 

I a pickj 

1 16 Slickenjides. [Book VI. 

pick, is drawn over the vein with fomc force, the 
mineral begins to crackle like fulphur excited by 
cledricity ; in a few minutes after which the laminsc 
explode with violence, and fly out as if they had 
had been blafled with gun-powder, infomuch that 
the weight of forty tons has been blown out toge- 
ther. Theie dangerous efFefts deterred the work- 
men from proceeding for fevcral years j but at 
length it occurred to them that this power might 
be ufed for the carrying on of their works with 
better advantage than by the common method of 
blading with gun-powder. Accordingly a work- 
man makes a fcratch with his tool upon the joint 
of the flickenfides, and runs away as fall as he can, 
to efcape the explofion ; which, it is faid, loofens as 
much of the rock as ten men would have brought 
away in three months, by the ordinary methods. 


Chap. 15.] 

I "7 3 

Chap. XV. 

Difinitim of this Genus .^•^Various cwifotmd Sttnet* 

IN a ftrift fenfe all earths and ftones, as they cxift 
in nature^ may be denominated compound, as 
there arc none which are wholly fimple. By com- 
pound earths, however, is here meant fuch as are 
formed of two or more kinds of ftony matter^' and 
which in general conftitute a mafs of an heteroge- 
neous appearance. la treating of thefe fubftances, 
the arrangement of M. Daubenton appears the 
moft perfect and commodious. 

Mixed Stows, 


Quartz and fcintiUadng fpar 
Quartz and fchirl . - - 
Quartz and fteatites - - 
Quartz and mica . - • 
Tranfporent quartz and mica 

Quartz in grit and gem ftonc 



Granitello. . 
Qaartzofe fteatitet. 
Micaceous quartz. 

Micaceous cryftaL 

II Garnet on grit 
2 Garnet in grit 


F4>- ••■".. 

1 1 8 Compound Earths. [Bo#k VI. 

Quartz in grit and mica - - Micaceous grit. 
Quartz in grit and calcareous fi Cryftallized grit. 

matter - - - - - (.* Gritinftaladiitc*. 
Quartz in fand and opake C fandy and fili^c- 

ftone 1 o"^ breccias. 

r fcintillating fchiftas 

Quartz in fand ^nd fchiftus | hornftone, trap. 
Quartz in fand and zeolite - fcintUlating zeolite. 
Scintillating fpar and pafte, or 

cement, offchirl 
Semi-tranfparent (lone, with ^jafpered agate, or 

opake ftone 

Schorl and mica 



i agatized jafper. 


Schiftus and mica - - 
Schiftus and marble 

Serpentine and marble - 

Ponderous fpar and calca- 
reous matter 

micaceous fpathofe 

micaceous fchifto*. 
Florence marble. 
f I green Egyptian marble. 

2 Tea-green marble. 

3 green antique marble. 

4 green ntarblc of Suza« 

5 green marble of Varalta. 

alkaline ponderous fpar. 



Quartz m fand, fchiftus, and 7 ^ , ^ ^ 
- . > Rough whet- flone. 

mica ------^^ 

Quartz, gem, and mica - - garifet rock, 

.Quartzofe pafte, fcintillating fpar | 

in large fragments, and fchorl^ , ' 

Quartzofe pafte, fcintillating fpar 7 fcrpcntine, hard/n. 

in large fragments, and fchorl \ /'*''»'' 


Chap. 15.] Porphyry i Granite^ ^c. 11^ 

Quartz, fchirJ, and fteatites - tuberculous rock. 
Quartz, fcintillating fpar, "and 7 

fchirl \^zr^xxt. 


Quartz, fcintillating fear, fchirl 7 

J . > granite. 

and mica ----- ^^ 

Of skyeral genera, more or 

LESS IN. NUMBER, UNITED IN ^ univerfal breccias. 

BRECCIAS - - - - - J 


I Fragments of porphyry, with a paftc of 

with a pafte of 

r I i-ragments ot porphyry 
ies.} porphyry. 

j 2 FragmeiKs of granite, 
L fchorh 

1 4 Chap, 

[ "o 1 

[Book Vr- 

Chap. XVI. 


LMva.^^Differint Kinds. — Progrefs of a River ^Lova.-— Cmv- 
foMtui Parts of Lava.^PuMict Stoste.'-^Ba/altes.'^rapp.'m^ 
Tirra PuxzoIomo. 

I. T AVA is of very various appearance, accord- 
1 ^ ing to its compoficion, and its more or lefs 
pcrfeft ritrification.' The materials of which lavas 
conlift, arc the common fubftanccs to be found every 
wKcre in the earth, namely, ftones, metallic ores, clay, 
fand, &c. ; and as there is room for great variety in 
the combinations of thefc fubftances, the melted 
mafles formed by them muft in different clrcum- 
ftances be very various. Some lavas are very 
compaft, and receive a beautiful polilh, exhibiting 
great variety of colours and forms. Others are ex- 
tremely porous, and mixed with fcoriae or drofs. 
On the different confiflence of lavas depends their 
capacity for being converted into mould, capable 
of fupporting vegetablear. Some lavas have a ten- 
dency to crumble into dufl immediately on iflTuing 
from the crater ; others are a perfeft glafs^ and are 
calculated to refill for a long time every approach 
towards dilTolution. 

Lava, when firft thrown out fi-om the crater of a 
volcano, is an uniform liquid mafs, and flows down 


Chap. 1 6.^ Courje of a River of Lava. i ai 

the fide of the mounuin with confiderable rapiditf. 
From Iqfs of heat, however, its furface is (bon 
converted into a tough and black cruft, which, as 
it becomes thicker, gradually impedes the progrcfi 
of the fluid lava which is contained within it. This 
crult is frequently broken, when the ftream of kva 
refembles a river with toafles of ice floating on its 
furface. Fluid lava ibmetimes flows for a cobfiu 
derable diftance, under the tenacious fcum, and 
again appears beyond it in all its fplendour. In the 
jiight time the courfe of the lava appear^ like 
flame, but no real flame ever exifts, unlefs the lava 
in its progrefs happens to meet with combuftiblc 
matter. In the day-time its courfe is marked by a 
-thick white fmoke. 

Mr. Kirwan divides lavas into three kinds, the 
cellular, the qompafb, and the vitreous. AU lavas 
are mqre or lels magnetic, give fire with fl:eel, are • 
of a granular texture, and melt without the addition 
of other fubftances. The cellular lavas are fuch as 
have undergone only the firft and lowed degree of 
fuflon, being juft foftened and heated fufficiently to 
^xpel the fixed air contained in the matter from 
which they are formed, which feems to be argilla- 
ceous date; hence they abound in fmall cavities 
occafloncd by the expanflon of that air. The fpe- 
cific gravity of fomc lavas from thefe cavities is fo 
fmall) that they float for fbme time on water. From 
this circumftance they have fometimes been mifta- 
ken for pumice-ftone ; but they difier from it, be* 
caufe their texture is never filamentous. The per- 
fectly vitrified lavas muft have been expoied to an 


122 Pumicefime. [Book VI. 

immcnfe heat, as they arc very difficultly fiifed 
without addition. M. Sauffiire has ingcnioufly 
imirarcd all the different kinds of lavas, by diffe- 
rent degrees of fufion of the earthy fubftances from 
which they are formed. M. Bergman analyzed a 
fpecimen of the perfeft kind, and found an hundred 
parts to confift of forty-nine of filiceous earth, 
ihirty-five of argillaceous, four of calcareous earthy 
and twelve of iron. 

The beds of lava arc deepeft and narrowcft near 
the crater, and broader and (hallov^cr as they ad- 
vance, unlefs Ibme valley intervenes. Puniice- 
\ ftones lie at a ftijl greater dillancej and from thcie 

!| obfervacions, fays Mr. Klrwan, extinguifhed volca- 

i noes may be traced. The quantities of matter 

I thrown out of volcanoes at one eruption, are often 

fo great as to cover a fpacc of country of many 
I miles, and to be many vears in cooUng. 


I II. PuiMiCE-sTONE fccm.s to be rather a volcanic 

I ejcjftion than a volcanic produft. Its colours are 

^ %xcyy v;hite, and rcddiih brown. It is hard, roiigh, 

I porous, conlilh of (lender fibres parallel to each 

\ other, is very light, and with difficulty gives fire wick 

I ftcel. It fcems to have been originally an afbeftos. 

decompofed by the a<5lion of tire. One hundred 
parts contain from fix to fifteen of magnefia, with a 
fmall portion of calcareous earth; the remainder is 
chiefly filex. Pumice -Hone fwims on water. It is 
ufed to fmooth rough furfaces, and, in a (late of 
powder,' in various branches of manufadlure, chiefly 
for poll filing. 


Chap. 16.].. . Ba/alus. 123 

IIL Basaltes is a ftonc of a dark grey cqIouTj co- 
vered with a fcrrugineous cruft, and generally cryf- 
tallized in opake triangular or polyangular columns. 
When it is annorphous*, and breaks into large, 
thick, fquare pieces, it is called trapp. When 
heated red hot, and quenched in water, it becomes 
by degrees of a reddifti brown. It melts without 
mixture into a perfect flag. One hundred parts con- 
tain fifty-two filiceous, fifteen argillaceous, three 
calcareous, twoof magnefian earth, and twenty-five 
of iron. Bafaltes fometimes is found in large co- 
lumns with Convex and concave articulations, fo as 
to refemble an artificial ftrudlure: of this kind ^re 
the bafaltic pillars in Ireland> called the Giant's 

Glafs, in cooling, has been known to affume the 
regular bafaltic form. Sir William Hamilton re- 
marked, both in Sicily and Naples, that fuch lavas 
3s have run into the fea are either • formed into re- 
gular bafaltes, or have a great tendency to that 

IV. Terra Puzzolana or Terras, is a volcanic 
produftion, of a grey, brown, ycllowilh or blackilh 
colour, loofe, granular, or dyfty and rough, porous 
and fpongy, refembling a clay hardened in the fire, 
and then reduced to a grofs powder. Its moft diftin- 
guilhing property is, that when mixed with about 
one- third of its weight of lime and water, it hardens 
very fuddcnly, and forms a cement which is more du- 
rable in water than any other. Its indurating power 
feems to arife from the dry ftate of the half-baked 

* Not of a regular form. 


124 Terra Puzzolana. [Book VI. 

argillaceous particles, which caufcs them to imbibe 
water very rapidly, and thus the deficcation of the 
calcareous earth is accelerated. It is found not 
only in Italy, but alfo in France, in the provinces of 
Auvergne and Limoges, and alfo in England and 
elfewhere. According to Bcrgman*s analyfis, one 
hundred parts contwi from fifty-five to fixty of 
(iliceous earth, nineteen or twenty of argillaceous, 
five or fix of calcareous, and fi-om fifteen to 
twenty of iron. 


Chap. xyO [ taj 3 

Chap. XVIL 


Vfu 9/ MitaU,^^Their Froptrtm.^-JVtigbt^ Opacity, MalkM- 
Utyt Du^iliiy, FufibiUiy.'^Mix 'imih tach other^^^Tbeir Imfiam' 
mability, — Calcinati9n,F^Eniire and Simi'metalsj'^Pirfe& amd 
imperfe^f.^-'Naiural Hiftwry 9f Mttah.'^Wwkingof Mlfus.^^ 
AJfaying.'^Smibing^'-^lJnion wtb Acids ^"^ASion ofotbirSui^ . 
fiances en Metals. 

METALLIC fubftances are valuable for their 
durability^ their capacity of afluming and 
retaining all forts of forms and impreflions ; the 
doicnefi of their texture, which renders them ca- 
pable ofpolilhi the firm cohefion of their particles, 
which renders them highly proper for utenfils, 
where great ilrength is required to be combined 
with moderate bulk. Several of the metals are alio 
highly ufeful as medicines. 

The firft ^ndmoft obvious property of metals is 
their remarkable weight, in which they exceed all 
other bodies. By this circumftance they are diftin« 
guilhed from earths; the lighted of metals, which is 
tin, being fcven times the weight of water,^ whereas 
the heavieft earth is only between four and five 
times the weight of water. 

Metallic fubftances are by fiir the moft opake of 
all bodies. The moft opake ftoae divided into 


1 26 opacity of Mitah. [Bck^ VI. 

thin plates, has more or lefs of tranfparency, where- 
as gold is the only metal which admits of being re- 
duced to fuch a degree of thinnefs as to afford the 
fmalleft perceptible tranfmiffion ti light. Gold in 
leaf, which is about .^^^^^ part of an inch in 
thickneis, tranfmits light of a lively green colour; 
but filver and brafs leaf are perfeftly opakc 
-The opacity of metallic bodies renders them ex- 
ceedingly propef for reflcfting the rays of light, as 
nobodiespoffefs this property in fo eminent a degree. 
Thus we obferve that glafs reflefts objefts ver)^ imper- 
feftly, unlefs coated with metal, as in looking-glailcs. 
The capacity of reflefting light depends on the de- 
gree of polifli and the whitenefs of furfacc, confe- 
quenriy white metallic fubftances refleft a greater 
quantity of light, and arc more brilliant, than thcfc 
which are coloured. 

' A property which feems to belong exclufively to 
vtnetals, and yet not to all of thcmi is malleability. 
This confifts in a capacity of havihg their fubftance 
extended, and their lurf ice increafed, either in breadth 
^r length, without bfeing liable to frafture. The 
capacity, however, of being extended in length 
and breadth is not exaftly'the fame, for metals 
•which admit of extehfion under the hammer can- 
not always be drawn into wire, which property is 
diftinguifhed from the other by the term duAility. 
Beanng always reduces metals to a (late of rfgi- 
dity and brittlenefs. To remedy this, the metals 
are generally heated red hot, and cooled again flow- 
ly; in this cafe their malleability will be increafed, and 
this is called ahnealing them. Crammer fays, that 
I ■ if 

Chap. 17.] Malleability of Metalsy 6ff. lay 

if gold is annealed iajthis manner the leaf will be 
opake, and that the tranfmiflion of light through 
ordinary gold leaf depends on fmall cracks and 
flaws in the metal. If this affertion is troc, it 
will in a great meafure eftablifli the.perfed: opacity 
of metallic fubftances. Metals, when hammered, 
give out a degree of heat, and at the fame time be- 
come brittle 5 and the only method of reftoring 
their malleability is to expofe them to the aftion of 
heat, and to fufFer as much of this as poffiblc to fijc 
itfelf in their fubftance, by cooling them gradually. 
From thefe fads it is probable that the malleability 
of metals, as well as fluidity and elaflicity in general, 
depends on the particles of bodies being kept at a 
diftance by the prefence of latent heat. 

Metals are the bell conduftors of eledtricity of all 

Metals are fufible by heat, and one of. them 
(mercury) is well known to cxifl: in a ftate of fufion 
in the ordinary temperature of the atmofphere* 
The particles of metals have a remarkably ftrong 
attraftion for each other, which is evinced by Imaj^ 
portions of metal, when in a ftate of fufion, having 
a tendency to aflume a globular form. 

Moft metals will uniformly mix in all propor- 
tions with each other ; the fpecific gravities, how* 
ever, of thefc compounds is fcarcely ever fuch, ts 
would be nvithematically deduced from the fpecific 
gravities of the metals employed, on the fuppofi- 
tion of their junftion by fimple contadt. Mixtures 
of metals arc more fufible than might be cxpefted 
from the degree of fufibility of their component 



Calces of Metals. [Bdok VI-. 

therefore conveniently ufcd 


parts> and are 

It is found that metals which, after having been 
fufed, are fuflfered to cool gradually, evince a ten- 
dency to affume a regular figure, and to cryftallize 
in general in an o£bahedral form. 

Metals, in dieir fplendid or reguline ftatc, have a 
confiderable attraction for oxygen, and are in this re- 
tpc€i nearly allied cothe inflammable fubftances. Iron 
burns with a bright flame when heated to a certain 
degree, and immerfed In vital air ; and a mixture of 
tin and nitre produces a violent deflagration. Zinc, 
irficn heated and a£bed on only by common atmo- 
spheric air, burns with a bright and vivid flame like 
phofphorus. It is remarkable that mixtures of 
metals calcine more eafily than the metals in a (epa-^ 
rate ftate. Thus a mixture of lead and tin, neither 
of which, when feparatc, aflTord heat and light, in 
riieir mixture produce both, and the calcination is 
remarkably rapid. From the addition of oxygen 
the weight of the calx is greater than that of the 
quantity of the metal from which it was produced. 
In fomc metals, however, the attraftion for oxygen 
is fo weak (as is the cafe with the finer metals) that it 
b only by particular proceffes that they can be com- 
bined with it. Metals united with oxygen lofe their 
Iplendour, malleability, and texture, and are deno- 
minated calces. 

According to the old chemical theory, the calx 
of a metal was deemed a fimple fubflance, and was 
called the earth or bafis of a metali ^d ic was fup- 
pofcd that this eardij united with phlogifton, confti- 



(Jhip-. ty,3: f'irfeS and iw/fi^fe£t Mods-, 6?n x«f-. 

tuted the metal in its pcrfcdl ftate* It is now^ 
howevet, very fatisfadorily provedj that the me- 
tallic ftatc is the more firtiplc, and that the calx is 
a combination of the metal with oxygen. Me- 
tals are reduced from the calciform to the reguline • 
or metallic ftate, by heating them in corttadt with 
fubftantes which have a Wronger, attraftion for 
oxygen than themfelves, as charcoal, taUow, &c. *" 

Metals which are malleable are. called entire me- 
tals ; and thofe which are brittle, femi- metals. Me- 
tals are alfadiftinguifhed into perfe& and imperfeAi 
The perfedb are fuch as are not calcined by being 
heated in contadt with air^ and are three in num- 
ber^ filver> gold, and platina: the other metals 
are calcined in thofe circumftances, and are called 
imperfeft. It will eafily be underftood that thefe 
diHerences merely indicate different d^rees of at- 
traftion for oxygen i and as in this refpe^t, as well 
t% in regard to inalieability, there are numerous 
gradations among the metals, it will be neceflary 
to treat feparately of each meral as a dillind fub« 
ftance^ I ihall begin with fuch metals as have 
moft refemblance to the earths> and are therefore 
called femi-metals, and conclude with thofe which 
have the metallic properties in the higheft perfec- 

Thofe metallic bodies with which we are at 
prefent acquainted^ and which we can reduce to the 
metallic or reguline (tatc^ are the following feven* 

• The name regulus wa^ givin by the fancifol alchemifts to 
the metallic button, found in the bottom of the crucible after 
an ailay,' from the idea that this button contained gold, which 
they called the king of metals. 

V<M^H^^ K !• Arfeniq 

13© Arrangement cfMitaUicSuI(/tafues. [Book VI. 





10. Iron. 

11. Tin. 

12. Lead. 

13. Copper 

14.' Mercury 
15. Silver. ^ 


16. Gold. 

17, Platina. J ^ 

I. Arfenic. 
a. MoJybdcna. 
3. Tungftcin. 





8. Antimony. 

9. Zinc. 
Of thcfe the nine firft arc called femi -metals, 

from defeft of malleability j the five following im- 
perfeft metals, from their being calcineable by heat 
and air ; and the three laft, pcrfeft, from their ca- 
pacity of refifting the action of heat and air without 

Metals exift in a ftate of nature in four difierent 
forms. [^ ■■ 

T. They are found in a native ftate of purity, 
with all the metallic properties. Gold is always 
found in this ftate -, filvef, copper, mercury, bif- 
muth, and arfcnic often ; iron feldom j and lead, 
zinc, and regulus of antimony ftill more rarely. 

2. Metals are found in the ftat^ of earth or calx, 
without the metallic afpcft, and often refembling 

3. The common ftate, however, in which me- 
tals are found is that of ores. In this ftate they 
arc eitlier combined with fulphur or with fome iiic- 
tali the.moft common of which is arfcnic *. 

4. The laft ftate in which metals are found, is 
that of a combination with faline fubftances, and al- 

f In this ^lid the following ftate they are (Slid, in technical lan- 
guage, to be miruralized'i that is combined with fome Other mi- 
neral fiibftancc. 

• ' - ' 6 moft 

Chap. 170 Ores of Metals. . 13 1 

mofl: always acids* Th^ vitriolic acid is moft fre^ 
quently found combined with metals^ viz. zinc> lead» 
copperj and iron. The carbonic acid is alfo a com- 
mon mineralizer, and the arlenical and phofphoNc 
acids have likewife been difcovered in combination 
with metals. 

Metallic fubftances are more commonly found 
in mountains than in plains, and almoifl: always in 
fvich mountains as form continued chains. It is in 
the ftratified mountains that metals moft abound, 
where the inclination of the ftrata, in confequence 
of the convulfions of nature, brings a variety of fub- 
Qances into view, which muft otherwife have been 
for ever concealed beneath the reach of human in- 
veftigation. Thore are entire mountains which 
coniift of iron ore, but in general the metallic part 
of a mountain is very inconiiderable in proportion 
to the whole. The ores fbmetimes run parallel to 
the ftony ftrata 5 the layer on which the ore is placed 
is called the bed or floor of the mine; the other 
which covers i^ is called the roof. Sometimes, how- 
ever, the metallic ftrata, which are always more 
irregular than the other ftrata of which the mountzcfi} 
is compofed, interfedb the bodies which iurround 
them in a variety of directions. The metallic ores 
are accompanied with ftony matters, which feem to 
have been formed at the fame time. Thefe ftones 
are ufually quartz and fpar; they are called the rider 
or matrix * of the met^, and muft neither be con- 
founded with the mineralizing fubftance which is 

» So called from its frequently indofing the ore. The . 
fparry matters are alfo fometimes called by mberalogtfla 
ganguif. , 

K % intimately 

iji Mines* [Book VI. 

intimately combined with the metal, nor with the ge- 
neral mai^oCftone) of which the mountain contain- 
ing the metal is compofcd. It is obfervcd that the 
vegetables which grow on metalliferous mountains 
are dry, the trees fmall, finuous, and deformed, and 
the fands often exhibit metallic colours. Mineral 
metallic fprings are ufually found in the vicinity; 
by the examination of which, and of the fands over 
which they flow, a tolerably accurate judgment 
may be formed of the metallic contents of the 
neighbouring ftrata. . When metallic veins appear 
at the furface of the earth, the ground may be 
broken into with great probability of advantage, 
and the boring inftrument, by bringing up the (ub* 
ftances which compofe the internal parts of the 
mountain, together with the metallic minerals, 
fcrves to fhcw their quality, as well as the refiftance 
which may be cxpeded in digging. 

Before a metallic vein is wrought with a view to 
profit, it is necef&ry to afcertain the proportion of 
metal contained in it, and this is called allaying. 
In thefe fmall trials the fufibility of the mafs is in- 
ei^fed by the addition of three times the quantity 
of the black flux, which is made by burning together 
two parts of tartar with one of nitre. The alkali 
of this compound increafes the fiifibility of the 
ftony matter mixed with the ore, and confrquendy 
aflfords the metal an opportunity of feparadng fixxn 
it; while the charcoal contained in it, and which 
proceeds from the impurity of the tartar, abftrads 
the oxygen of the ore, and reduces the metal to t 
fegulinc form. 


•Chap. 17.] jtjfaying of Ores. 1J3 

When-thc operation has been properly performed, 
•the m^tal, or regulus, is found in the form of a but- 
ton at the hDttom of the mafs, and being weighed 
Ihews the proportion of metal contained in the ore. 

This mediod is ufed in reducing fmall quantities, 
as"in aflaying of ores, but would be too expenfive 
in large operations. Tfiey then mix the ores or 
tralces with the fuel, but let as little air as puffible 
pafs through it, as this would tend to re-calcin^ the 
metal. To prevent this efFeft, a particular fort of ^ 
<fcma?e is employed, in which charcoal is chiefly ufed. 
" It frequently happens that the fame minerals con- 
-tain the perfeft metals mixed with the imperfeft \ 
thefe are feparated both in the finall and large Way 
by heating the mixed mafs in contaft with air. By 
this operation the imperfect metal is reduced to 
a caljt, and leaves the perfeft metal in a ftate of 
purity. If the remaining metallic matter is ftill a 
compound, and contains two of theperfeft metals, 
thefe are feparated by expofing them, with as large 
a furface as poffiblc, to the adtion of a menftruum, 
which has the property of diffolving one of them 
without the other. 

There is alfo a method of aflaying in the 
humid way, by fubmitting the ores to the aftion of 
difFercpt acids j but this is not fo prafticable as the 

I n the extraftion of metak in the large way, the ore 
is pounded, walbed,roafted,l*melted, and refined. By 
pounding, the ftony matters are feparated from the 
metallic, and the whole being then wafhed on in- 
clined planes or tables, the ftony matter being, 
lighter is walhcd away, while the metallic remains 

K 3 behind. 




134 SmeUing of Meials. [Book VT- 

bchiad. The roafting or burning is intended to 
expel the volatile matters. Or«s which contui 
much fulphur muft be roaftcd in the open air, but 
fuch as contain but little may be roafted in the fijr- 
naces which afterwards ferve toftife them. Some ores 
are fufible alone^ others require to be mixed with 
different fluxes. The methods of refining metals 
are extremely various, and depend on particular 
chemical affinities, which will be rhentioned under 
the head of each metal. 

The. fairs, and of them the acids in particulaj^ 
have great efFeft on* metals. Metals unite widi 
acids into compounds, many of which cryftallizo. 
The corrofivenefs of the acid is abated by its union 
with the metal, but not in fo great a degree as by 
its union with the alkalies or earths. Neither is the 
point of faturation fb well marked in the union of 
gn acid with a metal as with an alkali. The fame 
acid may, in many cafes, be united to the lame 
metal in different proportions ; when the acid is ia 
excefs the mafe is deliquefccnt, when it is deficeot 
it fecms to produce little other efFed ,on the metal 
than to deftroy its texture, and reduce it to s^ friable 
^d earchlike flare. 

Every metal, however, is not diipofed to unite 
with every acid, though fome unite with alls 
others .with only one acid. The order alfo in which 
the acids attraft the metals is different from that 
in which they attra<5b the alkalis. Metals atcrad 
the muriatic acid mofl flrongJyj^ next the vitriolic, 
and h& the nitrous. Metals which diffolve in the 
fan^c acid differ ycry much in the forqe with which 


Chap. 17.3 ASion ifAdAm Mitds. 155 

they adhtre to it, fo that thef may be employed to 
precipitate one another. Thqs, if we add to the* 
folution of filver in aqua-fortis, quickfil'ver, it 
precipitates the filver j copper, the qdickfilvcr ; 
iron or lead, the copper 5 and zinc, which pre- 
eipitafies thefe, may idelf be precipitated by an 

The folution of metals in the acids is attended 
with, the efcape of an claftic vapour, and an effer- 
vefcence. This was formerly adduced among the 
proofs for the exiftence of phlogifton, which, united 
wirii a fmall quantity of the" water or acid, was 
fuppofed to conftitute this elaftic fluid, at the fame^ 
time that Ae metal, by its lofs, w^s deprived of its 
fpjendour, &c. This appearance is now proved to 
arife from a decompofition either of the acid ot 
the water, and the elalHc fluid differs in different 
cafes, according to the foqrce from which it derived 
Hs. origins Vrben it arifes from the decompofition of 
n^er, it is hydrogen or iitfla^imable gas, when 
from that of tha^ nitrous acid, nitroua gas,. &c. Be-" 
ibra the itietal can be difiblved, it 's ntceflary that 
it fhould be oxygenated; and therefore wheirics at- 
traflrion is iufficiently ftrong, it decompofes the acid 
or the water, by abftradiog their oxygen* It \m 
been alreiKly remarked, that the muriatic acid has 
the ftr<Higeft ;attra£bion for metals, and the nitrous 
lefs th^ft cither that or the vitriolic. From merely 
obferving the«a£lion of thefe acids on metals, how- 
ever, a dificFent conclufion might be drawn, for 
the nitrous acid a6ls with violence and rapidity in 
comparifon with the other two \ and the muriatic, 
K 4 when 

136 Aliion of Light mi^eat w Metals. [Book VT. 

when in its purcCt ftate, has the k aft aAion of tbe 
three. This fc^ming inconfiftcnqr depends on the 
difFcrcnt degrees of attraftion which the bafes of the 
different acids have for oxygen. The reaibn, there- 
fore, why foine metak cannot be diffolved in particu- 
lar acids, is, that they have not a fufficiently ftrong at- 
traflion for oxygen to decompofe the acid. If we 
fcparatc a metal from an acid by any fubftance which 
is not capable of depriving it of oxygen, we always 
obtain it in a calcined ftate. Thus gold, if precipitat- 
ed from its folution in aqua regia by an alkali, is a 
calx J but if precipitated by any of the inflammable 
fubilancds, as aromatic oils or fpirits of wine, or 
by cnother metal, it appears in the metallic form. 
IS metals are calcined previous to being united with 
acids, they produce no efcapeofgas, bccaufe being 
already furnifhed with oxygen, they have no ten* 
dency to decompofe the acid. 

Light appears to alter the colour and brilliancy 
0f fomc metallic matters, independently of the ao* 
tion of air i for when cxpofed to light in tranfparent 
ycffels well clofed, they become tarnifhed, and lofc 
their tr>ctallic- bciliiancy. 

Hesit applied to metals produces no other efieds 
than expanfion an^fufion, if the air is completely 
, excluded, unlefs carried to fuch a degree as to vola- 
tilize them; hut even in tjiat cafe, when the heat 
ceafes to a6t> they return to their original ftate. Me- 
tals, on. being converted into vapour,, boil like 
pther. fluids, and even gold and filver are capable 
of this ftate whfn ^6led on by a Jar^e concave 

Chap. 17.] Mim tfQmiuftBle Matters, 6?r. 137 

Moft of the combuftiblc bodies aft on inetaK 
Inflammable gas gives them a deeper colotir, and 
is capable of reducing fome of them to the 
metallic ftate. Sulphur, and its combinations 
with alkalies, called hepars, act powerfijlly oa 

From what is hitherto known of metals, there is 
every reafon to believe that they are fimpic 


[ 13« ]t [BookVL 

C H A p. XVIII. 


Natural Hiftory bf Ar/emc. — M9Jt of reducii^ it t» the meimSir 
Form.'^ff^hite EnameL'^Orpimint.^^Realiar, — Its V/e vt M*- 

'didne^^^A drtadftd Poifon ; houo to dettU it in the Bosifj--^ 
A Remedy fcr the Poifon of A^few. 

ARSjENIC IS often found native, in black heavy 
maffes, but not very brilliant. It has Ibme- 
times the metallic luftre, and reflefts the colours of 
tne rainbow s in its fraAure it is more brilliant thaui 
at its furface, and feems compofcd of a great num- 
ber of fmall fcales. Native arfcnic is very cafily 
known, when it has the metallic brilliancy arvi fcaly 
texture. Arfcnic, however, is more frequently 
found in the form of flowers, or mixed with certain 
earths. Cobalt ores contain much arfenic, and 
that which is commonly Ibid is brought chiefly 
firom the cobalt-works in Saxony. The ore \% 
thrown into a furnace, refemhling a baker's 
oven, with a flue or horizontal chimney, nearly 
two hundred yards long, into which the fumes 
pais, smd are condenfed in the form of a grey or 
Uackiih powder. This is refined by a fecond fub- 
limation in clofe veflels, with a little pot-afh to de- 
tain the impurities. As the heat is confiderable, it 
melts the flowers into thofe white cryfl^Uine mafies 
which are met with in cpnnincrc^ 


Chap*i8.] Kegviimf Atfim. ij^ 

The regulus is obtsuned from dits fobfiano^ 
which is a calx of arfenic^ by heating itwitK one- 
tenth of its weight of charcoal^ or of any undhious 
macten The mixture is put into a tall vcflel, and a 
gradual and gentle heat applied to the lower part 
of it, whik the upper is Jcept cool by the air. 
TKe arfenic, when nearly red hot, parts with its 
oxygen, and rifes to the u[^r part of the veflel, 
where it iscondenfed in die inctaUic form. To give 
it, however, its perfedt mcullic fplfendourand opa- 
city, the fublimation muft be repeated; 

The regukis of arfenic is of a bright yellowifii 
white colour, very ponderous and friabk, and fub^ 
jeft to tarnifh ac^ become black on expoliire to 
^. If heat is applied to the regulus in contaft 
•with air, it is volatilized before it. melts, and is at 
the fame time impeifedtly calcined. The fumes 
are dangerpus, and have a ftrong and offenfive fmell^ 
refembling that of garlic* 

The white^^alx of arfenic is (b far in a faline 
ilate as to be foluble in eighty times its weight of 
cold, or fifteen dmes that of boiling water. Whoi 
diftilled with the nitrous. acid, it decompofes that 
fluid by depriv'uig it of part of its oiygcn. The 
(jrfenic, by this addition of oxygen, is reduced to the 
(late of an acid lefs volatile than either the regulus 
or calx, but reuining the form of a white concrete 
fubftance. The oxygenated muriatic gas Ukewife 
reduces arfenjc to the flate of an acid. 

Arfenic readily melts with other fubfbnccs fo as 
to form glafs, and even promotes their fuiion. At 
firft it always renders the glaf^ milky, but by a coo- 


I40 . ^'fe/if Enmef. " [Book \a 

/tinuarion ofiicat thc^ arfcnic evaporates, and the 

- glafs 'becomes quite tranfpaTent. It is an ingrcdim 

in the whkc enamel dial plates ; and it forms thofe 

white fpirals which are com;non in the ftalb of 


Sulphur unites readily with ^rlentc inta a com- 
pound more fufible than the arfcnic itfelf. Orpimcnt 
is a con^bination of arfenic atid fulphur, of a yellow 
colour. It is found naturally in the earth, generally 
of an irregular form, and compofed of Ihining flex- 
ible laminae. Its fpecifie gravity, according to 
.Kirwan, is 5,315, who alfo aflfert^ that it contains 
one- tent^ part of its weight T^f fulphur. The fame 
author mentions, that realgar, or the red combina- 
•tion of arfcnic and fulphiir, contains fixtcen parrs 
of fulphur in the hundred, and is of tlie fpecific 
gravity of 31^05, Chapcal, hbwever, obfervfs 
• that the .difference between realgar and orpimtHt 
does not confift in the proportions of fulphur, no- 
thing more being neceflkry in oidfcr to cob vert 
orpinient into realgar, than expofure to aftrong 
heat. The violent action of arfcnic on the animil 
machine is much abated by combination withM- 
phur. Common white arfenic has fometimes been 
fuccefefiilly ufed in dofes of one-twelfth or one-fix- 
teenth of a gririn. Received, however, in any con- 
fideraWe quantity into the body, it produces drynfii 
of the mouth, heat in the throat, excruciating pains 
in the bowels, attended fometimes with vomiting «f 
blood, cold fweats, &c. Qn diffcAion, the bowels 
are found inflated and corroded. Many black afid 
livid fpots appear on the domach and fmall intef- 


Chap* 1S.3 j^tldote for the Poijon $fArfefik. 141 

tines, fomctimcs gangrenous. But thrfe figns arc not 
altogether to be depended on. Some of the arfenic^ 
5s frequently found, and may be eafily diftinguiflied. 
The powder is heavy, and eafily feperaies from the 
lighter contents of the bowels, by walhing with wa- 
terj the arfcnic always falling to the bottom. A very 
little of this is fufficient to give the frtiell of garlic, 
and tinge copper white, if heat is applied to it. 

It was formerly ufual to give mucilaginous drinks, 
or milk or mild oils, to perfons poifoned by arfe- 
nic. But Navier, a phyfician of Chatons, who. has 
made experiments to afccrtain the beft remedies 
againft the poifon of arfenic, has difcovered a fub- 
ftancc which combines with it in the humid way, 
and dcftroys, in a great meafure,^ its caufticity. 
This fubftancc is the calcareous or alkaline liver of 
fulphur, and is ftill better adapted to the intention, 
when it holds a fmall quantity of iron in folntion. 
When this niartialhepar is poured into a folution of 
arfenic, it is decompofed without emitting any 
fmcU, becaule the arfenic combines with the ful- 
phur, and forms orpimcnt, and at the fame time 
unites with the iron. Navier prcfcribes a dram of 
the liver of fulphur in a pint of water, of which he 
diredts a glafs to be taken at a tinie i or five or fix 
grains of dry liver of fulphur may be given in pills, 
a glafs of warm water being given after each pill. 
When the firft fymptoms are difl]pated, he recom- 
mends the fulphurcQus mineral fprings. Navier 
likewife approves theu!^>f milk, becaufe it dif- 
folves the arfenic as well as water, but he con- 

I4d Union cfAr/enic^ with othr Mttds. [Book VT. 

demns the ufe of oils^ which have not that pro- 
perty. ^ 

Arienic {hews a Orong difpofition to unite ^th 
all the metals except platina. By a mixture of it in 
its ordinary ftate with coppery a metal is produced 
lefembling filven It generally gives metals a white 
colour^ and r«oders them brittle. 


Chap. 19-3 [ H3 ] 

Chap. XIX. 


Short Aanmt of this Semi»mitaI.^^May ht reductd to om Jdfi.^tm 
A /caret Mineral. 

THIS is a mineral fubilance, which has tlQ 
lately been confounded with plumbago; but is 
now found to be a combination of a particular me- 
tallic fubftance with fulphur. It is of a blackiih 
colour^ and confifls of fhining laminse^ which have 
a degree of flexibiiity, fo as to be very difHciultly 
reduced to powder- 

Molybdcna reduced to its metallic form refcm- 
bles lead in colour and fpecific grivity, but is very 
brittle, eafily calcined and volatilized^ and will not 
mix with lead when in fulion. 

Molybdena is capable of being oxygenated fo far 
as to become an acid, in which ilate it is a concrete 
body, white and pulverulent, refembling chalk. 
This acid, heated with fulphur in a particular man* 
ner, is capable of being converted into a fubftance 
in every refpeft the frme as native molybdena. 

This mineral is fcarce. It is diftinguifhed froon 
black lead by a more fhining, fcaly appearancei and 
it marks paper with a more brilliant ftroke* 

'•■'•■•■ / 


I M4 I tBookTT. 

Chap. XX. 


T2f Oftof^ungftiin confoundid nulth that •fTin.-'^'iFhtre Jok^L 
'•^Modi of reducing it to tbt reguliru or metallic St ate^ 

TUNGSTEIN or wolfram is a particular 
metal, the ore of which has frequently been 
confounded with that of tin. The Ipccific gravity 
of this ore is to water as fix to onej in its form of 
cryftallization it refembles the garnet, and varies in 
colour, from a pearl white to yellow and reddilhi it 
is found in feveral parts of Saxohy and Bohemia. 
The mineral called wolfram, which is frequent in 
the mines of Cornwal; is likewife an, ore of this 
metal; in all thefe ores the metal is oxydated; and 
inlbmp of them it appears to be oxygenated to the 
itatc of an acid, being combined with lime into a 
true tungftat of lime ♦. 

The calx of this metal cannot be obtained free 
from the bodies with which it is united, without a 
particular procefs, which confifts in the alternate 
application of volatile alkali and marine acid> and 
the fubfequent addition of the nitrous acid, as long 
as red fumes are produced. This.calx or imperfed 
acid has the colour of brimftone, and is fcarcely fo- 
luble in water. By being fubmittcd in a crucible 

* Lavoificr*8 Chcmiftry. 


Chap. 20.] RegUlus (ftuHgfim* 14^ 

with charcoal, to a ftrong heat, a rcgulus of tung- 
ftcin may be obtained, which is a brown mafs, cort^ 
lifting of a congeries of nnetaliic globules ; and again 
becomes yellow by calcination. The regulus is pot 
afted on by the vitriolic and marine acids; the ni- 
trous acid, however, and aqua regia, adl on it, and 
by oxygenating it reduce it to its calciform ftate. 

M. Lavoifier recommends the following procefs 
for obtaining the calx of tungftein 2 Mix one part 
of oreoftungftcin with four parts of mild vegetable 
alkali, and melt the mixture in a crucible, which 
ought to be of platina; then powder, and pour on 
twelve parts of boiling water; add pale nitrous acid, 
and the tungftenic acid precipitates in a concrete 
form. Afterwards, to infure the complete oxyge- 
nation of the metal, add more pale nitrous acid, 
and evaporate to drynefs, repeating this operation 
as long as red fumes are produced from the acid« 

VouIL U . CH^r. 

C h6 ] 

[Book VI. 

Chap. XXL 


Natural Hifiory of Manganefi.'^Its EffeQi on Gla/t.^^^Reguha ef 
MetaL — Black Wath-^Mangantje contained in Vegetans,— 
V/is in the Arts* 

THIS metal is almoft always found in the ftate 
of calces, which vary much in colour and ap- 
pearanccj they are white, blue, yellow, red, dark 
green, and black, according as they are united with 
more or lefs oxygen, or contaminated with foreign 
fubftances* The darker coloured the ores, the more 
. oxygen they may be fuppofed to contain, as any 
procefs which deprives them of this principle al- 
ways renders them paler. Manganefe is alfo 
found cryftallized in a variety of forms* Many na- 
turalifts, judging by their colour, and the ochry • 
cruft with which they are often furrounded, have 
ranked the calces of manganefe among the iron ores. 
The black calx of manganefe gives a violet, pur- 
plifh, and fometimes a reddilh tinge to tranlparcnt 
glafs; but. when added in a fmall quannty to that 
which has a blueifh or greenifli caft, it produces 
only a flight duflcinefs, without a predominancy 
of any colour. 

The regulus of manganefe is very difficultly ob- 
tained. Its colour is a dufky white, but its mafles 
are irregular and uneven from imperfedt fuGon. Its 
frafture is bright and (hining, but it foon tar- 
♦ Ochre being an iron ore. 


Chap, a I.] Mangane/e found in VegetahUs. 147 

nifties and becomes blackifli on expofurc to air. 
When pulverized it is always magnetic, though it 
has not this property in the mafs, 1 f expofed to air, 
particularly in moift weather, it foon crumbles into 
a blackifh brown powder, which is fomewhat hea- 
vier than the regulus from which it was produced. 
The calces of manganefe retain their oxygen fo 
weakly, that part of it may be expelled by the ap- 
plication of a ftrong heat. They alfo part with 
their oxygen to unftuous oils. If half a pound of 
that 6re of magnanefe called black wad is well 
dried before the fire, afterwards fufFered to cool for 
about an hour, and then mixed with two ounces 
of iinfeed-oil, fmall clots will be formed, and in 
litde more than half an hour the whole will gra« 
dually grow hot, and at laft burft into flame. 

Maoganefe feems t6 be contained in the afhes of 
moft vegetables, and to it the blue or greenilh 
colour of calcined vegetable alkaK is owing. If 
three parts of alkali of tartar, one of fifted afhes, 
and one- third of nitre, are melted together, they 
form a dark green mafs, which being di0blved ia 
water, aflfords a beautiful green foludon ; thb being 
filtered, on the addition of a few drops of vitriolic 
acid becomes red, and after a few days a brown 
powder is feparated, which has all the properties of 

The vitric^c, nitrous, and marine acids diflblve 
the regulus of manganefe in the.ufual ways. The 
black cabt is nearly infoluble in the acids, unlefs h 
is deprived of part of its oxygen by the addition of 
feme inflammable or metallic fubftancie. The 

L a snaring 


rtoUt Colour of Glafs. [Book VL 

marine acid, however, digcftcd with the black 
calx of mar>ganefey diffolves it without addition, io 
proportion as it lofes fome part of its oxygen. The 
oxygen uniting with part of the muriatic acid, ren- 
ders it volatile, and converts it into oxygenated 
muriatic acid. Tlie permanent folubilitjr of the 
bbck calx of manganefe in the acids, depends on 
the acid, or fome fubftance mixed with the acid, 
abftrafting piirt of ies oxygen. The mangancfc 
feparated irom its folution in acids by alkalies, is in 
the form of the white or iirperfeft calx, which, 
however, becomes black by being heated in con- 
taft with air. 

In the dry way the calx of manganefe connbines 
with fuch earths and faUne fubftances as are capable 
of undergoing fufion in a ftrong heat. The violet 
colour which it communicates to glals is liable to be 
dcftroyed by combuftible fubftances. From, this 
circumftance we may conclude, that the property 
of colouring glafs depends on the calciform ftate of 
this metal, and that it is loft when any body ab- 
ftfads its oxygen and reduces it to a regulus. 

Mar^ganefe in its metallic form will not unite 
with fulphur, but nielts readily with moft of the 
' metals. Gold and iron are rendered more fufibic 
by a due addition of manganefe, and the latter me- 
tal is rendered more duftile. 

Manganefe has hitherto been ufed chiefly by 
glafs- makers and potters; but the important dif- 
coveries of the effcd of oxygenated muriatic ackl, 
prepared by means of manganefe, in bleaching, wiU 
no doubt extend its utility to feveral other manu; 
faftories. Chap. 

Chap, aj.] [ 149 ] 

Chap- XXII. 


Vatural Hifiory of NickeL^^Metal bo-w ohtained^'^^Detonates ivitb 
Nitre, — Has a ftrong Repulfionfor Siher, and JttraSiion for 
Sulpimr, — A ufelefi Mineral. 

THIS metal derives: its name from the mineral 
in which it is contained- It is found united 
with fulphur and arfenic. Its ores have a coppery red 
colour, are almoft always covered with a greenifli 
grey cfflorefcence, and have been miftaken for 
ores of copper. The ores of nickel often contain 
cobalt and iron. Moft of the fulphur and arfenic may 
be driven off hy long continued roafting, and the 
occafional addition of charcoal, which prevents the 
arfenic from being rendered more fixed by calcina- 
tion J and the green calx which remains may be 
fiifed by the ftrongeftheat of a fmith's forge, toge- 
ther with two or three times its weight of black * 
ilux. By thefe means a regulus may be obtained, 
which, however, is very far from being pure, as it 
contains much arfenic, cobalt, and iron. In this 
ftatc it is of a white colour with a tinge of red, and 
has a granulated texture. When this metal is ren- 
dered more pure by treatment with fulphur, char- 
coal, volatile alkali, and nitre, it becomes extremely 
infufible, lofes fomewhat of its reddifli tinge, and 
acquires a confiderable degree of malleability. 
Nickel may be freed from fulphur and arfenic, but 
L 3 it 

1 50 Regulus of Nickel [Book VI, 

ic cannot be accurately purified from cobalt and 
iron, for it is cbnfidcrably attraftcd by the magnet^ 
and gives flgns of containing cobalt, after tbc ut« 
mod pains have been taken to obtain it in a pure 
ftate. It affords a blue folution with volatile al- 
kali, and in nitrous acid its folution is of a full 

From its magnetic property, nickel has been 
cbnfidered as a modification of iron ; and by its pro- 
ducing a blue colour with volatile alkali, it has been 
fuppofed to be an alloy of copper with various mc- 
tillic fubflances. Chemifls, however, are now very 
generally agreed in confidering nickel as a difUnft 
metallic fubftance. 

M. Sage affirms, that when four parts of oil of 
vitriol are diflillcd with one part of the regulus of 
nickel in powder, the fulphureous acid pafles over; 
the refidue is grcyi(h, and, being diffolvcd in diftilled 
water, produces the ijioft beautiful green colour. The 
cryftals obtained from this folution are foliated, and 
of the colour of an emerald. According to M. 
Arvidfon, the vitriolic acid forms a green fait, in 
decahedral cryftals, with the calx of nickel. 

This calx is eafily folublc in the nitrous acid, 
and cryftallizes in rhombic cubes. According to 
M. Sage, all the other folutions of nickel, or its 
calx, either in the muriatic acid or in vege- 
table acids, are more or lefs green. It has been 
faid, that the nickel contained in cobalt occafions 
the fubftance known under that name to produce 
a green colour with acids. Nickel differs from 
a cobalt 


Chap. 2 2.] i?/ Repulfionfor Silver. 151 

cobalt in not being feparatcd from acids by the 
addition of any other metal. 

Nickel detonates ♦ with nitre j this detonaticn 
afforded Mr, Arvidfon a method of difcovering 
the prefence of cobalt, which no other proof 'has 
rendered fenfible. Nitre has likewife the pro- 
perty of augmenting the intenfity of the hya- 
cinthme colour, communicated to glais by the calx 
of nickel. The calx of nickel, fufed with borax, 
likewife produces a hyacinthinc colour. The 
calces of nickel are of a green colour. 

The moft remarkable properties of the regulus 
of nickel are, a repuUion for filver, and a ftrong 
attnuftion for fulphur. It has fo ftrong an affi- 
nity for fulphur,^as to attrad it from moft other 

Nickel combines by fufion with fulphur into 
a hard mineral of a yellow colour, with fmall 
briUtant plates, which, when ftrongly heated in 
ContaA with air, deflagrates and emits very lumU 
nous fparks, fimilar to thofc afforded by iron when 
forged. Cronftedt informs us that this meul 
is foluble in liver of fulphur, and forms a com- 
pound rcfcrabling the ores of copper. The fulphur 
can only be feparated from nickel by repeated 
fufions and calcinatioQS.^ 

Cronftedt affirms that nickel forms, with, bifmuth^ 
a britde aiid fcaly regulus« Nickel has not yet bcc4 
applied to any yfe. 

^ laBamesj an4 explpdes Asdd^oly* 

L 4 C H A F. 

[ IS* ] 

[Book VI. 

Cm A p. XXIII. 


Natural Hiftorj of Coh alt. '-•' Analogy hetween this Metal anJ th4 
hlue colouring Matter of Vegetables, ''^Mode of ajfaylng it,-^Mhres 
of Cobalt. '^Smalt, or Porwder Blue, — Vfes of Cobalt in the Arts. 
^•^Curious ffmpathetic Ink, "^Change ahU Landfcaf€<,^^Untcn 

. ^tth other Metals* 

COBALT has never been found native, that is 
in a metallic (late, but is almofl always cal- 
cined or united with arfenic, the arfenical acid, 
fulphur, iron, vitriolic acid, &c. Minerals con- 
taining cobalt arc frequently of a pink colour, which 
arifes from the prefence of arfenical acid, and its 
colour is deftroyed by fire, in proportion as the 
acid is diffipated. When united with vitriolic acidj 
it alfo is fometimes reddifh : the effeft of acids on 
cobalt points out an analogy between it and the blue 
colouring matter of vegetables. 

To affay cobalt ores, the operations of pound- 
ing, walhing, and roafting muft be all employed. 
The cobalt remains in a date of black calx, more 
or lefs deep with refped to colour j this is mixed 
with black flux and a fmall quantity of decrepitated 
fea fait ; the fufion is performed in a forge heat in a 
covered crucible, which muft be flightly agitated, to - 
precipitate the nnetal as foon as the fufion is com* 
plcte. The metallic button is fometimes found to 
confift of two diftin<£l fubftances, cobalt being 
4 Vppcrmoft, 

Chap. 23.] Smalt or Powder Blue. 153 

iippcrmoft, and bifmuth beneath ; a ftroke of the 
hammer readily feparates them. 

The regulus of cobalt is of a whitilh grey or fteel 
colour, hard, brittle, of a dull clofe- grained frafture, 
and moderate fpecific gravity. It has about the 
fame degree of fufibility as cOpper ; does not eafily 
become calcined 5 and its calx is of fo deep a blue 
colour as to appear black. Cobalt expofed to heat 
does not melt till it is well ignited. It appears to 
be very fixed in the fire, and it is not known whe- 
ther it can be volatilized in clofe veflels. If it is 
fufFered to cool flowly, it cryftallizes in needle- 
formed prifms, placed one on another, and united 
in bundles. Cobalt, melted and expofed to the air, 
becomes covered with a dull pellicle, which is a 
calcination analogous to the rufting of iron. 

The richeft mines of cobalt are in Saxony. The 
ore which is forked there in the large way contains 
a confiderable quantity of arfenic, which is driven 
off by heat, but is coUefted in long channels 
of wood, and prefervcd for fale, as was intimated 
before. After the ore has been kept fome time in 
the furnace, there remains a dark friable fubllance, 
which is the cobalt in the form of a calx, and call- 
ed zaffre. This is mixed with the ordinary ingre- 
dients of glafs, and melted with i violent heat, fo as 
to produce the common blue powder called fmalt, 
which is a pounded glafs. Some of this is mixed 
with flints and alkaline falts, and then fold under the 
name of fapphire to the manufa<5hirers of porcelain 
and conamon Delft ware, for tinging their glazing 


1^4 Pajles in Imitaiim of Sapbirc. [Book VL 

Powder blue, or azure, is obtained by grindiag 
fmalt in mills, and afterwards wafliing it in water. 
This lalt operation is performed in a calk filled 
with water, and pierced with three openings at dif- 
ferent heights. The water of the uppcrmoft cock 
carries out the fined blue. The larger partidcs 
fall more fpeedily, and the azure brought out by 
the water of the three cocks forms the dificrem 
degrees of finencfs, known by the names of azure 
of the firft, fecond, and third fires. Powder and 
ftone blue, ufed by laundrcfles, is a preparation 
made by the Dutch from the coarfe fmalt. 

A fmall quantity of the calx of cobalt tinges glafs 
of different Ihades, according to the quantity ufed. 
One grain of cobalt to feven thoufand of the giafs, 
renders it very blue : hence the paftes in imitation 
of fapphire are produced. Stained flint glafs is made 
by fixtecn parts of fand, eight or ten -of pearl afli, 
and metals in difrcrent proporcions. 

Cobalt diffoWes readily in aqua-fords, both in its 
metallic ftate and in that of a calx. If we take a 
folution of its calx in that fluid, and add a quan< 
lity of water to it, and then let it (land a while, it 
turns red, and on evaporation forms cryftals of the 
fame colour, and by this it may be diftinguiflied 
from all other metals. This folution forms a red 
fympatbetic ink, which appears on the paper by 
beat, and again difappcars by cold. 

Aqua-regia diffolves cobalt more ealily than 
the muriatic, but not fo eafily as the njtrous, acid 
This folution is a celebrated fympathedc ink. If it 
is diluted with a fufficicnt quantity of water to pre- 

Chap. 13.] Curms Sympathetic M^ 155 

vent its aAion on paper^ and then ufed to write mth^ 
the letters are invifible as foon as the clear folution 
becomes dry j but if the paper is held to the fire 
for a (hort time, they appear of a fine green colour; 
iTvhich again difappears by removing it, and fuflfering 
it to cool. If held to the fire too long, the green 
colour becomes permanent. "From thefe two inks 
a very curious changeable landfcape may be made. 
The trunks of trees, houfes, &c. may be painted 
with common colours, fo as to reprefent winter. 
The verdure, the fruits, and the flowers may be 
depifbed in different fhades of the two inks. On 
aproaching the fire the landfbape will gradually be 
changed from a winter to a fummer fcene. The 
trees will begin to fhoot out their foliage, and the 
flowers and the fruits will, by degrees, aflume the 
appearance of maturity. The vivid parts will again 
fedc, on being removed fi-om the heat, and the land- 
fcape refume the wintry afpeft. 

It was formerly thought that the green colour 
produced by heat in the fympathetic ink of co- 
balt, arofe ft-om the metallic fait being cryflallizedi 
and afterwards attracting a fuificient quantity of 
water from the cold air to diflblve it, and caufe it to 
difappear; but it is proved, that the marine fait of 
cobalt, diflblved in water, aflumes the fame colour 
when expofed to a certain degree of heat. 

The vitriolic acid in a concentrated ftate does not 
diflblve cobalt without the afliftance of heat, when 
the acid is decompofed, and comes over in fulphu- 
reous fiimes. The cobalt is in part calcined, and in 
part converted into a cryflalline fait foluble in water, 


15^ Union of Cobalt with other Metals. [Book VI. 

and which may be precipitated by lime and by alka- 
lies, in the form of a rofe-colourcd powder or calx. 
Diluted vitriolic acid afts upon the calx of cobalt, 
and forms the fame fait. 

Cobalt unites with all the metals except filver, 
lead, quickfilver, and bifmuth, but does not pro- 
duce any remarkable or ufeful compound with any. 
It is feparated from acids by zinc in the form of a 
dark-coloured powder, but not by iron. 

A mixture of nickel with the calx of cobalt very 
much injures the colour which the latter communi- 
cates to glafs. The following procefs is one of the 
beft for feparating tbem when the cobalt is in con- 
fiderable quantity : Saturate a folution of the roafted 
ore in nitrous acid, and drop it into liquid volatile 
alkali. The cobalt then is inftantly re-diflblved, 
and affumes a garnet colour i when filtered a grey 
powder remains on the filter, which is the nickel, 
fhc cobalt may be precipitated by any acid* 



Chap. 24.] ^ t 157 3 

Chap. XXIV. 


External ^alitits of Bifmuth.^^A ptrwerful Diffoher of Earths 
— Pearl White^ a peinicious Cofmetic'^^urtoui Experimsfit.^-' 
A metallic Compofition^ *wbich melts in boiling IVater.^^Various 
Vfes ofBifmuth in the Arts. 

BISMUTH is extremely brittle, fo that it may 
be eafily feparated, and even reduced to pow- 
der by the hammer. When broken it exhibits at 
the place of frafture large Ihining plates, jJifpofcd 
in a variety of diredlionst It is confiderably pon- 
derous, and is of a yellowilh white colours when 
in thin plates it is in fomc degree fonorous. It is 
very fufible, and melts at a temperature not ex- 
ceeding 460° of Farenheit. 

Bifmuth is fcarcely altered by expofure to air and 
light. In clofed vcflels it fublimes without alteration j 
it cryftaliizes the mod eafily of any metallic fub- 
ftance. If bifmuth is kept in fufion in contadwich 
air, its furface becomes covered with a pellicle, 
which changed into an earth of a grcenifli grey or 
brown, named calx of bifmuth. Nineteen drachms 
of bifmuth, calcined in a capfulc of glaft, afforded 
M. Baume twenty drachms thirty- four grains of 
calx. Bifmuth heated to rednefs burns with a fmall 
blue flame, fcarcely fenfible. Its calx evaporates 
in the form of a yellowifh fmoke, which condenfcs 
on the furface of cold bodies, into a powder of 


158 Pearl mUe. [Book VL 

the (ame colour, called flowers of bifinuth. This 
powder owes its volatilization only to the rapidity 
with which the bifrauth burns ; for if it is expofcd 
in dofc vcflTels to fire, it melts into a grecnifli glafi 
without fubliming. Geoflfroy the younger obfcrvcd, 
that the flowers of bifmuth, which rife the lafl:, arc 
of a beautiful yellow, refembling orpimcnt. 

The grey or brown calx, the yellow flowers, and 
the glafs, are nothing more than combinations <^ 
this metal with the bafe of vital air^ which arc not 
reducible without addition. 

Calx of bifmuth is one of the mod powerful dif- 
folvers or liquefiers of earthy bodies, or of the calces 
of other metals, and gives a yellowifli tin^ to 
glafl^cs, into the compofition of which it cnten. 
Bifmuth is alfo readily calcined by nitre, but with- 
out detonation. The alkalies have litde efl^dt on 
bifmuth ; when applied, however, in a cauftic ftatc^ 
they diflblve part of the metal. 

The vitriolic and muriatic acids do not a£t on 
bifmuth, unlcfs afTifted by heat. The nitrous acid, 
however, diflfolves it with great rapidity, and du- 
ring the folution copioufly emirs denfe red va- 
pours. This is one of thofe folutions from 
which the calx is moft eafily feparated by water. 
On being dropped into water a bright ponder is 
dcpofited, called magiftery of bifmuth. This is 
fuppofed to be the fame with the fubftance called 
fearl white j well known as a cofmetic; for whea 
rubbed on the Ikin it gives it a white Jhining co- 
lour. But in reality all thcfc mctalfic fubftances 
ultimately darken the Ikin, for a cak when long 


Chap. 24.] PemioQUs EffeSs of Co/metics. 159 

cxpofrd to the air^ and the exhalations of aninnal 
bodies, parts with its oxygen to the inflammable mat- 
ter, arid affumcs a dark colour. Bifmuth, moreover, 
poflefTes many properties in common with lead, and 
there are fome inftances in which the external ufc 
of this metal has produced the word cfiefts. 

Solutions of bifmuth arc particularly afFe6ted by 
fetid odours, which proceed from putrefying fub- 
ftances. This feems chiefly to depend on the ful* 
phureous parades which are exhaled in thofe pro- 
cefles, and is illuftrated by a ftriking experimenL 
If charafters arc written with a folution of bifmuth 
on the flrfl page of a book of fifty leaves, and the 
laft page is impregnated with a fmall quantity of the 
liquid liver of fulphur, a fliort time afterwards the 
hepatic vapour, carried by the air which circulates 
between all the leaves, arrives at the other extremity 
of the book, and converts the colourleis charaders 
marked on the flrft page into a deep brown. It 
. is affirmed that the hepatic gas pafles through 
the paper; but it is fufliciently proved that the air 
carries the gas in this manner from one leaf to an- 
other, fince the eflfed does not take place wheft the 
leaves are glued tdgethen This experiment evincea 
in the cleared manner the impermanency of the 
beautifying effect of the calces of bifmuth. 

The nitrous folution of bifmuth is without colour^ 
^nd when well iaturated afTords cryftals without 
evaporation. But by evaporation and cooling thefi: 
cryftals may always be obtained. The nitre of biT* 
muth detonates feebly^ and with reddifli fcintilLu 

i6o Compound which melts with RttkHeaL [Book VL 

tions ; after which it melts and inflates, leaving a 
calx of a grcenifli yellow colour. This fait cx- 
pofed to the air lofcs its tranfparency, at the &mc 
time that the water of cryftallization is diflipated. 

The acetous acid diffolves bifmuth flowly, and \a 
fmall quantities. 

Inflammable gas alters the colour of bifmuth^ 
and gives it a violet tinge. Sulphur unites widi 
bifmuth, cfpecially with its calx ; in which ftarc 
it refembles crude antimony. It unites with all the 
metals, except zinc and regulus of cobalt, and takes 
away their malleability and duftility, and increafcs 
their difpofition to calcine; it alfo increafes. their 
fufibility, hence its ufe ia foldering lead and tin. 
If added to a mixture of lead and tin, in tcrtain pro- 
portions, it produces a metallic compound, which 
retains the ftate of fluidity in the heat of boiling 

Bifmuth is chiefly ufcful for mixing with tin to 
produce pewter, rendering it handcr, and better to 
be caft into molds. It is alfo ufed in making 
printers* types ; for by giving a greater tenuity to 
the fufed mafs, it fits it for receiving a neater im- 
preflion. An amalgam for foiling glafs globules 
is made of ten parts of mercury, two of bifmuth, 
and one of lead and tin. It may be fubfl^itut- 
cd inftead of lead in the art of cupelling the pcrfeft 
metals, becaufe, like that metal, it has the pro- 
perty of flowing into a glafs which is abforbcd by 
the cupels. 


Chap. 24.1 Ottt oftifmHth. \%t 

Bifmuth is often found native. It as alio found 
United with arfenic, fulphur, iron>' and fonofetimes 
in a Calciform ftate. The fulphureous ore of bil^ 
muth is of a whitifh grey, inclining to blue; it haa 
the brillianqr ^nd colour of lead ore or galena, and 
almoft always exhibits fquare facetSj but it i& never 
found in fragments truly cubical. It is very rarcj 
and is found at Bailnas> in Sweden* and at Schnec^ 
burg, in Saxonyi 

VodL M Chap; 

[ 'H 3 


Cu AT. XXV. 


Natural Hijiory pf ^Jnttvtony. — Regulus, — Snou^ of JntimtRj .-- 
Calcination of AntimoOy. — Combinations luhh AciJs, — Buttrref 
Antimony. — Antimomal IVine.^Ujis of Aiitimotty in ALdkiwi, 
— F lores Antimonii. — Gla/s of Antimony, — Crocus ef Antimny. 
Sulphur of Antimony, -^Tartar EmetiC'^James^ s Pvwder, 

THE fubftance, which is commonly known by 
the name qf antimony, is a combination of 
that metal with fulphur. This mineral is of a 
blackifh grey, in brittle plates or needles, of various 
magnitudes, joined together in different forms. It 
is fometimes mixed with other metals, particularly 
lead and iron, and is very common in Hungary, and 
in fbme of the provinces of France. From this ore 
the regulus of antimony is feparated by fufion. The 
antimony then forms a mafs of metal at the bottom 
of the veflel, while the other matter becomes a 
fcoria above it. 

The appearance of antimony is bright, approach- 
ing, when very fine, to that of filver. It is very 
brittle, and it is compofed of oblong plates or la- 
minae. When melted it forms a fmooth mafs 
like other metals, but upon breaking it, we find the 
plated appearance or^* the infide. The plated ap- 
pearancc depends on the cryftallization, which be- 
gins at the part that firft congeals. The regulus 
of antimony, which is prepared for commercial pur- 

Chap* ct5.] Snow of AntimMj. 163 

pofes, is caft into flat and circular pieces, which 
have a Cryftallization on their furface, in the form 
of the. leaves of fern. 

In fufibility antiixiony holds a middle rank, re- 
quiring a perceptible degree of red heat before it 
becomes fluid. In the fame degree it emits va-. 
pours copioufly if frelh air is admitted, which al-. 
ways promotes the volatility of metals, Jf thefe 
fumes are condenfcd, they form a white powder. 
In particular circumfl:ances they cryftallize. They 
are, indeed, a perfciSl metallic calx, to which the 
names of argentine, andfnow of antimony, have been 
applied* This fubfl:ance is fo highly charged with 
the oxygenous principle, as to be foluble in water^ 
and to approach to theiiature of an acid. 

To calcine antimony by heat and air alone, let- 
the metal be powdered, then lay it on a broad Ihal- . 
low veflfcl, and apply heat not fufEcient to convert 
it bto fumes. This operation cannot be well per- 
forated, unlefs the antimony is in a ftate of minute 
divifion, fo as to prefent a large furface to the air* 
The procefs muft be conducted with caution at the 
beginning, on account of the fufibility of this com- 
pound of fulphur and antimony; but in proportion 
as the fulphur is diflipated, the remainder becomes 
more rcfraftory, and the fire may be raifed to fuch 
a degree as to make the veflcl in which the antimony 
is contained red hot. The furface of the m'etal be- 
. comes at firfl^ tarnilhed, and foon afterwards it is 
changed into an earthy powder of a duflcy colour, 
which, by continuance of the procefs, becomes 
white, Thefe cjllces have a difierent degree of 
Ma frifibility ' 

1 64 VitrificaticK of Antknony. [Book Vt* 

frifibflity according to the dcgi-cc of calcinariofl. 
When little calcined a ftrong heat converts them 
into a glafs of an opakc or black colour. When 
further calcined mote heat is required, and the glaft 
is a deep yellow. When calcined to whitenefs, the 
moft violent heat will npt melt them without the 
addition of borax, and the mafs is then of a pale 
yellow. Here we obferve the effcft of the prdcncc 
of oxygen in rendering this calx lefs fufible, and 
depriving it of colour. Thefe calces may be re- 
duced, but moft readily when little calcined, bf 
adding an * equal quantity of black flux, or one- 
fourth of charcoal or foap. 

The foffil fisted alkali brings antimony nearcftto 
the ftate of the pcrfeft metah. For this difcovcry 
we are indebted to MargrafF, who melted two 
ounces of rc^lus of antimony with one of M 
alkali. He repeated the fufion eight times, and 
every time he ufed frelh alkali; but the three or 
four laft times he did not ufe quite an ounce of al- 
kali, but made ufe of a mixture of alkali and flint 
Every time it was thus melted the regulus loft fomc ^ 
of its weight, and the alkali, having diflblved pan 
of it, was tinged green. The remaining metal was 
always whiter and brighter, and acquired a fmail 
degree of toughnefs. The texture was much finer 
than before, and it would eafily amalgamife ^^^ 
mercury. The weight of the regulus was reduced 
to about one half by eight operations. With tk 
vegetable fixed alkali the cflfcft was firtiilar, but not 
fo remarkable. 


Chap. 2 J.] Butter <if Antimony. 165 

The rcgulus^ of antimony is calcined with great 
rapidity by the nitrous acjd, but the muriatic and 
vitriolic fcarcely aft on it, unlcfs aflifted by heat. 
By the union of antimony with all thcfe acids, 
faline compounds are produced, which are dcli^ 

Sy^fccnt, and which are decomp€)fcd by water, or 
le fimple application of heat. The oxygenated 
jnuriatic acid and aqua rcgia diflblvc the regulus of 
antimony with great facility, ^ 

But bcfides thcfe methods of affifting the aftion 
of the muriatic acid on antimony, there is another 
procefs for combining the muriatic acid with the 
regulus. A quantity of mercurial fublimate in 
powder being mixed with the regulus of antimony, 
the acid afts upon the antimony immediately, fo a« 
to render the mixing of them dangerous, from the 
corrofive fijmes which arife. The common way 
is to powder them and mix them, and heat being 
applied, the niuriatic acid of the fublimate attradts 
the antimony, and rifcs with it in the form of a very 
volatile compound, which cond^nfes in the neck of 
the retort, of a confjftence between folid and fluid, 
and \% hence called butter of antimony. It^is very 
cauftic, and is ufed to confumc the callous lips of 
ulcers, but is too violent to be ufed internally, ffit 
i$ fubjefted to a fccond operation, it comes ov^c 
fluid. The fame procefs is employed to combine 
other metals with the muriatic acid. When but- 
ter of antimony is thrown into pure water, ag 
jibundant white precipitate or calx fells down, 
which is a violent emetic, and is known by the 
pame of powder of algaroth, 

UZ The 

1 66 jhtimony, a violent Poijbn. ^BookVI. 

The vegetable acids alfo aft upon antimony 
weakly when applied to it in its metallic ftate, bet 
much more ftrongly when it is (lightly calcined. A 
folution of this kind was formerly ufed under the 
name of antimonial wine. A quantity of the rcgu- 
lus was caft in the form of a cup, which was occa- 
fionally filled with wine, and having ftood a day or 
two, it became emetic. The quantity of antunony 
diflblved was very fmall, but was difcoyerablc on 
adding an alkali, and precipitating it. 

To give crude antimony any aftion as a medi- 
cine, it is necefiary to aeftroy a part of the llilpha'*, 
and alfo in fome meafiirc to calcine it. The more 
fulphur it retains, the lefs aftive it is. If we calcine 
it too much we alfo deftroy its efFeftsj for in the 
ftate of a white calx it has little or no medical ciE- 
cacy. The florcs aritimonii is a preparation in 
which the antimony is nearly deprived of fulphur, 
and at the fame time fiirnilhed with fome oxygen. 
It is very violent in its effefts^ a very minute 
quantity producing ccnvulfions and vomidng. 
Antimony indeed may be reduced to fuch a ftate as 
to affeft the body in fmaller quantities even than 

When antimony' is combined . with fulphur, 
and urged with a ftrong heat, it afliimes'the appear- 
ance of glafs. The glafs of antimony, though not 
much employed as a medicine, is very ufeful as a 
f)rernTiinary to_ the molt valuable preparations. 
Few of the metals, indeed, havp {o much at- 
trafted the attention of chemifts as antimony, and 
its preparations have b?en accordingly very numc- 


Chap. 2 5-] Crocks ff^ Antimtmy. 167 

rorus. To avoid, therefore, unneceflary prolixity, 
it will be proper to confine 'the readier*s attejltion to 
thofe which have been found mod ufcftil. 

By deflifgrating antimony with nitre, the metal 
is calcined, as well as when expofed to' heat in con- 
taft with air. The antimonium calcinatum of the 
London Pharmacopoeia is prepared by throwing a 
mixture of eight ounces of antimony, with two 
pounds of nitre, into a crucible heated to a white 
heat. The white matter is burnt for half an hour, 
and, when cold, is powdered and walhed with dif- 
tilled water. This preparation is fo inert, that it 
has been doubted whether it is capable of any aftion 
whatever on the human body. 

When the antimony and nitre are in equal quan- 
tities, they form a more aftive-compofition. The 
mixture burns with violence, and ought to be in- 
jefted, in fmall quantities at a time, into the heated 
crucibJe. After the combuftion there remains a 
mixed matter, partly of a dark red, and partly 
whitifh. Upon melting, it feparates into a heavier 
part of a deep red, and a faline part above of a 
paler colour. The former is the objeft of the 
. operation, and is called crocus of antimony. The 
College dirqfl: a fmall quantity of fea fait to be ufcd 
in this preparation, which promotes fufion, and 
probably increafes the aftivity of the compofition. 

Fixed alkalies have a great degree of aftivity 
with crude antimony, on account of their attraftioh 
for the fulphur. The eafieft mode of combining 
them is fufion. The firft effedl of the alkali is to 
combine with the fulphur, and fpfm a liver of 
M 4 fulphur^ 

l69 Tiartar Emetk^ [Book VL 

fulphur, which by a continuance of heat iecms to 
^UTolye the reguliis of antimony. This connpound 
is readily diflblved by bojlbg wa(erj and if we add 
to the folution an acid, the metallic matter and ful- 
phur are depofited of a yellow colour. This lub^ 
fiance, .however, which is called fqlphur anpnnonii 
prsecipitatum, may be obtained in an eafier man- 
ner, by boiling crude antimony in a fblutioo of 
alkali, and then precipitating the fulphurate^l anu* 
mony with the vitrioU<: acid. 

The antimonium tartarifatum, or Sifrtar ^metic^ 
may be obtained cither by the ufe of the crocas- or 
the glafs of antimony- The former is, however, 
preferred by the London. College, who adopt the 
following iproccfs: Take of crocus of antimony 
powdered one pound and an halfi cryftals of tartar 
two pounds, diftilled water two gallons: Boil 
them in a glafs vcffcl about a quarter of an hour; 
filter the liquor through paper, and fet it by to 
' cryftallizc. Tartar emetic confifts of the acid of 
tartar united to vegetable alkali and antimony par-r 
tially calcined. 

The pulyis antimonialis of the pharmacopoeia, 
which is thought to be nearly the fame as James's 
powders, is prepared by expofing equal parts of 
antimony and hartfliorn Ihavings to a moderate 
heat, with a free accefs of air. With refpcft to 
the peculiar merits of Janies's powders, they have 
never been proved either in theory or pradice. 
The circumftances upon which the effcdb of 
antimonial preparations depend are well knowi^, 
and though we canngf with certainty afcertain 
I the 

Chap* 45»3 Jamefs Pimdirs. 169 

the procels of Dn James, there is no reafoa 
to think that it is preferable to that of the 
pharmacopceia, in the preparation of the pulvi^ 
antimonialis. The love of myftery, however, has 
always had an influence over mankind, and therein 
no reafon to believe that the peiiod for its ceHatiou 
is at hand. 

The rc^us of antimony is employed in die 
manu&Aure of printers ^peS| and in making 


I -i'To ]' [ftookVI. 

• ' , - ' . ' ' . '. ' t ' 

Cha?.' XXVL 


i. - ■ ' , 

€tneral Defcription of this MetaL^^Fhilofofher^s Wccl — Ihm 
nuith dcidi^'^Wbite Vitriol ^"^Pttmathm of Zinc^vuitb Nitn.^ 
ComhinatioH tvith Metals. "-^Pewter. — Its UJe in Fire-ix^rks^ 

Natural Hiftory of Zinc. '^Calamine. — Black Jack, BrApt 

how made,"f'Tutty^ — Pinchbeck. 

THIS metal is in fome degree malleable, and 
therefore holds a middle place between the 
femi-metals and metals, though it is ufually referred 
.to the former divifion. Its appearance is blue and 
brilliant, and when broken it is found to be cryftal- 
lized in narrow plates. It melts when red her; 
if heated in clofe veffels to a vivid red or 
white heat, the whole of it rifes in vapour, 
and may again be condenfed without any change. 
When heated, however, in contad: with air, it bums 
rapidly with a white flame and crackling noile, and 
is converted into a white, fofr, and flocculent fub- 
ftance, called flowers of zinc, or lana philofophorum. 
If the zinc is burnt in a deep crucible, this calx at- 
taches itfelf to the upper part of' it, though fome 
part is always loft even in the deepeft veflcl, which 
will admit the air with fuSicicnt freedom to main- 
tain the combuftion. If a gentle heat is applied no 
light is produced, and the furface of the zinc be- 
comes gradually covered by a grey calx, which 
phanges to white, by being afterwards heated in con- 

Chap. 26.] • fVbiie Vitriol. , 171 

t2& with air. Zinic is fo apt Co. undergo this 
change that it is difficult* to melt fmall pieces of it * 
into a mafs, for in the moment after they arrive 
at the mcltihg point they are covered with a. 
(kin, which prevents their union. The calx rf 
^inc is not very eafily reduced to a reguline ftatc, 
as the heat neceffary for this efFcft is apt to vblati* 
Jize the metallic produft. 

Zinc is readily afted on by all the acids, and no 
metal fhews a greater j^ttraftion for them. It pro-^ 
duces with them metallic falts, in which the acid is 
more neutralized than in the other metallic com- 
pounds of the fame defcription. The acids do not 
dcpofitthc zinc when they arediluted with water.. 

The concentrated vitriolic acid does not a£t on - 
?:inc, unlefs aflifted by heat, and it then gives out 
fulphureous fumes. It is diffolved, however, with 
rapidity, and without the afliftance of heat, by the 
fame acid in a diluted ftate, and this proccis is at-^ 
tended with the copious produftion of hydrogen 
gas, which indicates the decompofition of the wa- 
ter. From this folution may be obtained white 
vitriol, which, as well as the flowers of zinCji is em- 
ployed in medicine. 

The diluted nitrous acid adts on zinc with fingu- 
lar violence, and nitrous gas is fo copioufly difen* 
gaged, chat the mixture fometimes exhibits the apr 
pcarance of boiling. The folution is very cauftic^ 
and afibrds cryftals by evaporation and coolings 
which flighdy detonate on hot coals, and leave % 
calx behind. This fait is deliquefcent. The dir 
luted muriacip acid adts on zinc with the fame pro? 

171 Detonatim of Zinc. [Book VL 

du£lk)n of hydrogen gas as the vitriolic % but this 
folution does hot afford cryftals. 

The vegetable acids acquire from zinc a fweet- 
ilh tafte and ftipticity. The aftion of the fluoric 
and boracic acids on zinc are not known. Water, 
impregnated with carbonic acid, diOblves a confi- 
derable proportion of zinc. 

All the folutions of zinc in acids are precipitated 
by lime, magnefia, the fixed and volatile alkalis; 
y the latter re-difiblves the precipitate if it is added 
in excefs. 

Zinc has the property of decompofing icveral 
neutral falts. If it is confiderably heated with 
vitriolated tartar in a crucible, it dccompofes 
the fait, and forms a liver of fulphur, in the fame 
manner as the regulus of ^ntinmony does. In this 
experiment the metal feizes the Qxygen of the vitri- 
olic acid, and the acid paffes into the ftatc of fulphur, 
which the alkali diflblves. The hepar formed by 
this combination diffolvcs a portion of the calx of 
2lDC. All the vitriols are likewife decompofed by 


When pulverized zinc is added to fufed nitre, 
or projected together with that fait into a heated 
<»rucible, a very violent detonation takes place. The 
iN5kivityof the inflammation is fuch, that portions 
of Ijurning matter are thrown to a diftance out of 
the crucible, in fuch a manner as to require precau- - 
tion on the part of the operator. Only fmall quan^ 
titles of the mature fhould be caft into the cru- 
cible at once. The zinc burns by the affift^ 
jmcc of the oxygenous gas afforded by the nitrci 

. and 

chap. 16.'] Ufe of Zinc in Pewter. 173 

and is afterwards found in a calciform ftate^ 
itiorc or lefs perfcdk, according to the propOr^ott of 
nitre ufcd. Part of the calx combines with the 
alkali, and forms a compound folublc in water. 

Zinc dccompofes common fait, and alfo fal am- 
moniac, by fcizing the marine acid. The filings of 
zinc alfo decompofe alum when boiled in a foiucion 
of that fait. 

The relation of zinc to fulphur is remarkable, as 
it is the only metal which does not unite with it in a 
r«guline ftate. M. Morvcau, however, has difco- 
vcred, that the calx of zinc unites eafily with fulphur 
by fufion. 

The regulus of zinc is capable of being united 
with that of arfenic, but it more readily unites widi 
arfenic in its calciform ftate. Zinc diftilled with 
white aricnic deprived it of part of its oxygeh, and 
was converted into a calx, while a correfponding 
quantity of arfenic was reduced to a regulus. 

Zinc does not combine with bifmuth, and 
when thcfe two metals are fufed together, the bif- 
muth takes the lower place on account of its greater 
gravity, and may be feparated by a ftroke of the 
hammer. It will not unite with nickel. Its vola- 
tility renders it extremely dilEcult to combine it with 
metals which are of difficult fulion, as iron and 
copper* It is, however, united to feveral metals 
for particular purpofes in the arts. It is added in 
fmali quantities to tin, or to a mixture of tin 
and lead, in the compofition of pewter, which it 
improves both in adding to the whitenefs and bril* ^ 
Tiancy^ and tnqreafing the hardneis. It is employed 


174. Natural Hfiory of tine. [Book Vt^ 

in many alloys> particularly in tombac, prince's me- 
tal, ^nd the various kinds of brafs. Fine filings of 
zinc are ufed to produce brilliant fparks in fire- works. 
Some perfons have propofed to fubftitute zinc for 
tin in lining copper veflclsj the latter metal, in con- 
junftion with lead, having been fuppolfed infuffi- 
cientto prevent the dangerous effefts of the lead. 
Macquer allows that this metal fpreads more evenly 
on the copper, is much harder, and lels fufible, 
than the lining of tin, but objefts to it, becaufe it is 
Ibluble in vegetable acids, and has a confiderabte 
emetic power. Mr. De la Plance, however, has 
taken the falts of zinc, formed by the vegetable acids, 
in greater quantities tlian they can be contained in 
aliments which have been dreffed in veffels lined 
with zinc, without experiencing any dangerous 
efifc6b. Experiments are yet wanting to prove the 
fuperiority of zinc lining over that of tin. 

Zinc is found in the following dates : It is fome- 
dme^, though rarely, difcovered native in flexible, 
grcyilh, and inflammable fibres. Zinc in its ore is 
generally in the form of a calx ; when the ore con- . 
tains no other metal but zinc it is never in any other 
fo/m, but it is often mixed with other ores, which 
contain fulphur and arfenic, and thefe muft be eva- 
porated by roafting. The richeft ores are compaft 
and ponderous, and are called lapis. calaminaris, or 
Calamine, they are found in the parifli of Holywell, 
in Flihtfliire. 

MargraflT has afcertained the quantity of.\zinc 
contained in diflTerent ibrts of calamine : 


Ch^. a,6.]; Making of Bra/s. ^ 175. 

Pam. Parts.. 

Calamine, from nearly ^^ ^.^^ . 

Cracow - - - i 

Calamine, from England i6 — — - 3 — 

—7 — from Brcflaw 16 ■ 4? ■ . ■ 

from Hungary 16 » 2| ■ 

— — from Holywell 16 — - 7 ■ ' 

. In one hundred parts of lapis calamjnaris were 
found eighty-four of calcined zinc, three of calcined 
iron, about one of pure clay, and twelve offilicegus. 
earth, according to Bergman, 

There is another fpecies of mineral ufed ia 
making brafs called blende, mock lead, or black 
jack, which confifts of zinc mineralized by fulphur, 
and fometimes by iron. 

The method of making ordinary brafs is as follows: 
—Copper in thin plates, or, which is better, copper 
reduced (by being poured* when melted into water) 
into grains of the fize of large fhot is mixed with 
calamine and charcoal, both in powder, and expofed 
in a melting pot for fe veral hours to a fire not 
quite ftrong enough to melt the copper, but fuffi- 
cient to reduce the zinc, and convert it into va- 
pours. Thefe vapours penetrate the copper in 
proportion to the furfecc expofed to their aftion, , 
changing its colour from red to yellow, and aug-* 
menting its weight in a great proportion. When 
they make brafs, which is to be'caft into plates, from 
which pans and kettles are to be made, and wire is 
to be drawn, they ufe calamine of the fined fort and 
in greater proportion than in the compofirion of 
common brais. 

' . .. ^ . Tutty 

176 Pincbhck, 6?^ [BotJc Vf . 

Tuttyis the flowers of zinc taken from the furnaces 
in which the ores containing this metal are wrought. 
It varies in colour and confiftence according as the 
calx is more or Icls perfcA, and is mixed with more 
orlefs of an argillaceous fubftance. Newman fajs, 
that the lapis tuti^ is compofed of clay beaten up 
with a fmall quantity of lapis calaminaris. 

Zinc and copper, when melted together in dif- 
ferent proportions, conftitute what arc called pinch- 
beck, &c. of different fhades of yellow. Margrafl^ 
melted pure zinc and pure copper together in a 
great variety of proportions, and he found that 
eleven, or even twelve parts of copper, bang 
melted with one of zinc, gave a molt beautiful 
and very malleable tombac or pinchbeck* 


Ghttp,a7-] E *7y !• 

Ghap. kt^^ii. 


kxtenfivi Utility of ibis Metal. ^-Tts Propertits,^Natural kiftofy 
hf Irmr,'^iiigU'6iiotus.'^ Bkod'^time$,'^Tbt Loai/tMi^'^ 
Emery.^^Ocbris.'^Smilting of Iron^^^Forging of IronJ^^Mak^ 
ing of Sttd^^^Trnpering of Steeh^^Caft StotL^^rtat Diffofi^ 
tion in Iron to unite wuitb other Bodies •^^Green Vitriol, how pro- 
€ttred,'^PruffiaM Blue^^^Ink, ^^Inflammation of Sulphur and • 
Iron^i^Tinning of Iron ^^^Freparations*of Iron ufedin Medicine. 

OF all metals> and I might perhaps be juftiiied 
in adding, of all mineral fubftahces^ the moft 
generally ufeful is iron. To fpecify its lifcs would 
be to produce a catalogue of everjr thing diat con« 
tributes to the fuftcnance and the convehidnce of 
life. By the afliftance of this metal we till the land, 
and obtwi the fruits of the earth in greater abun- 
dance and perfection than we could by any other 
means ; by its agency we are enabled to penetrate 
the earth itfelf, ind procure whacew^ it contains 
that may be ufefuLor ornamental to man ; there is 
itrarcely a mechanical trade> which could be con* 
dudted on the prefent principles without its did, 
and many of them could not even exift were we de- 
prived of its even in domeftic life our fafety^ our 
comfort, and our pleafure, all feem in fbmc mea- 
fure to depend on this moft valuable production of 
the earth. As the quantity of thisj as well as of 
ht^t other minerals, which appear «tmoll neceiTary 
yoL,IIj» N to 

. rj 8 Natural. Properties cf Iron. [6ook VL 

to focial exiftencC) muft be limited, I have often 
tiiought that the want of a fufEcient fupply, whichy 
on the fuppoficion of the prefent fyftem of chirigs 
being continued for ever, muft at fome time ccccf- 
farily take place, forms a forcible argument againft 
the abfurd and ignorant hypothcfis of the eternity 
of the world. 

The external^ appearance of diis metal is wctt 
known, and its hatxlnefs and elafticity are (een in the 
various inftruments and utenfils which are fbimed 
of it. 

It is the moft fonorous of all the metals,, except 
copper i but iii fpccific gravity it is ihferior to moft 
of them^ being only about feven times and a half the 
weight of water. Iron has a confiderablc fmelly 
dpecialiy when rubbed or heated. It likewife has 
a very perceptible ftyptic taftc. 

Iron is very dinaile, and may be drawn into- 
wire as fine as a human hair ; and it is fo tenaciovs, 
that an iron wire of one tenth of an inch diameter 
will fupport a weight of fifteen hundred pounds^ 
Iron may be ignited, or at leaft made fulScicntly hot 
to fet fire ta brimftone, by a quick fucceffipn of 
blows with a hammer 5 but it requires a moft intenfe 
heat ,to ftife it, on which account k is brought into 
fhape by hammering while it is in a Jieated flate. 
iron is alfo poflefled of another property, which fup- 
plies in^a^at meagre the purpofesoffufion. When 
peces of common foft iron are heated to a certaia 
degree, and are fuddenly taken out of the furnace and 
expofed to the air, we obfcrve their furfacc covered 
over with an appearance of varnifti which proceeds 



Chap. 27.] fFby Steel Jlrikes Fire with Flint. 1^9 

from the furface of the metal being pardy fufed. 
If two pieces of iron in this ftatc are ftruck toge- 
ther, they unite very firmly, and this procefs is 
called welding. It is diftinguifhed from all other 
metals by being attraftcd by the loadftone. Ano- 
ther property, which .diftinguifhes iron from all 
other metals, is that of ftriking fire with flint. This 
phenomenon depends on the aftual inflammation of 
fmall particles of the metal^ which prcfent a large 
iurface to the aftion of the air, and which arc heated 
by the friction which feparates them from the mafs^ 
lb as to difpofe them to inflammation. Thefe par- 
ticles are feldom larger than the two hundredth 
part of an inch in diameter, and when examined 
by a magnifieri are foand to be britde, of a 
greyifh colour, refembling the fcalcs of burnt 
iton. Attother proof of the inflammability of 
Iron is, that iron wire, heated at on^ end, and 
plunged in a jar of oxygen gas,' burns witli confix 
derable rapidity, and with a very brilliant flame* 

Iron is by far the rhoft abundant in nature of all 
the metals. It is not only contained in almoft 
every foffil, particularly in thofe which are Colour^^ 
ed, but makes a part of vegetable and animal mat- 
ter. With refpeft to tlie ores of iron, hoWevcr, 
as they are very numerous, it will be neceflfary only 
to notice thofe from which the metal may be cf*- 
trafted with advantage. In thefe ores iron exifts 
either in the metallic or calciform ftate, or mine- 
ralized by different fubA:ances« 

Native iron is known by its colour and mallea- 

ttlity. It is very rare, and is only found occafion* 

N 2 • ally 

i8o • Natural BJiory of Iron. {Book VI. 

ally in iron mines. Some naturalifts think di2t 
thefc apparently native fpecimens of iron have been 
produced by arC» and have been buried in the eard 
by accident. 

In the Philofophical Tranfadions for the year 
1788^ vol. Ixxviii. is an account of a mafs of native 
iron, weighing by admeafurement about three hun- 
dred quintals, which lies in the midft of a wide 
extended plain, in the middle of South Americki 
in latitude 70** 1%^ fouth, and at the diftance 
of feventy leagues eaft, one quarter ibu£h» 
6rom the hamlet of Rio Salado. It has the 
appearance of having been liquid, and bears the 
imprelllen of human feet and hands of a large iize, 
as well as of the feet of large birds common in diat 
country.- The extraordinary ^adt of fiich'a ms& 
of iron being found in the center of a vaft traft of 
level land, where there are no mountains, nor evea 
the fmalleft (tone, within a confideraUe difiance, 
projeduig above the furfac? of the eatth, is referred 
1^ the writer of this artick to an ancient volcanic 
explofion, of which there are fome veftigcs near it 
The fame fuppofidon is urged with equal probabi- 
lity to account for the produ6tion of another mais 
of native iron, in the fhape of a tree with its 
branches, which the author aflert&j on indubitable 
authority, is known to cxift in diefc immenfe forcfts. 
Some fpecimens of the iron were prcfentcd to the 
Royal Society, who afterwards depofitcd them ia 
the Britifli Mufeum. That ^argjc mafies of iron wcic 
really obferved in thefe fituations there is no reafon 


C3iap. 27. J Eagle Smes^ Blood SitmeSy 6fr. 181 

to doubt, but I (hoyld rather attribute the fiippo-. 
led impreAions to accidental refemblances. 

The largeft quantities of iron ores are in a calci« 
form ftatc, as in ochres, bog ores, &c. which are 
dilpofed in ftrata, in the manner of ftones. The 
ajtites, or eagle ftones, are a variety of the bog 
ores J they are in different forms, commonly oval 
or polygdnous, compofed of concentric layers, 
difpofed round a nucleus, which Is frequently 
moveable in the centre of the ftone. The haema- 
tites, or blood ftones, are named from their colour, 
wliich is commonly red. The loadftone is a dull 
iron ore, the varieties of which are diftinguiflied 
\by their colour, 

Emery is a grey or reddifli iron orc^ it is very 
hard and refraAory, and is found in abundance in 
the iflands of Guernfey and Jerfey. It is reduced 
into powder in mills, and in this ftate is ufed to po« 
Wh glals and metals. Spathofe iron ore is a calx of 
iron combined with cretaceous acid; it is.ufually of 
a wMte colour. Nature likewifc prcfents iron in a 
faline ftate, united to the vitriolic acid, and forming 
green vitriol. This fait is particularly found in 
mines which contain pyrites. Iron is often foiind 
united to fulphur, and then forms what are called 
mardal pyrites. This metal is alfo found combined 
with arfenic, both being in the metallic ftate. 
There is alfo a black iron ore, which is in fome 
mcafure attrafted by the magnet. Iron is fome- 
times found in the form of a blue powder. In this 
ftate it is called native prufTian blue. It is mixed 
wich vegetable earths^ and efpecially with turf. It 

N 3 was 



i8a Natural Bftory of Brmu [Book Vl. 

was difcovercd fomc years ago, that iron b often 
united witli the phofphoric acid. The m\]ddy c^ 
bog ores arc fomctimes of this nature. 

The ores of iron do nr)t afford the metal unlefi 
urged by a great heat. Sonne ores are melted widi- 
out addition 5 but it is neccflary to aflifl: the fufxm 
of others by calcareous matters, The limeftoncs, 
the iron ore, and charcoal, are alternately thrown 
into the furnace, ^nd the whole is covered with a 
layer of charcoal. The-nmeked ore is reduced by 
the contad of the coaly matter, and is then luffercd 
to run into a cavity ufually formed in fand. The 
metal in this ftate is called crude or caft iron. A 
vitreous matter, called flag, p?.ffes after the iron, 
and confifts of the ftones which were added to faci- 
litate the fufion. The metal thus obtained has no| 
the leaft duftilityj but it is deemed better in pro- 
portion as its colour is darker. 
"^The caft iron is carried to be reBned in a fbroc 
furnace, v^ith a hollow hearth, in which it is fur- 
rounded with charcoal, where the fire is urged by 
bellows till the metal begins to foften. When it is 
in this ftate, it is repeatedly ftirred, in order that it 
may prefent a larger furface to the air. By the ac- 
tion of the heat and air it emits fparks, which pro- 
ceed from the confumption of a quantity of plum- 
bago, or black lead, which is contained in the crude 
iron, and which it is commonly fuppofed to acquire 
from the fuel during the procefs of fmcltmg ♦. 

* It conMs of carbon^ wit;h about one tenth of its weight of 


Chap. 27.} Siderlte, Steeh ^c. 183 

The iron, by this mode of refining^ lofes, belkics 
€he plumbago, a quantity of fideritej which Berg>r 
man fuppofed to be a peculiar metal, but which 
is now found to be a. combination off iroa and i^u>f>- 

After the iron has been kept in this fituadon a 
certain time, it is carried to a large hammer, gene«- 
rally. moved by water, where it is /bnned iato.blirf^ 
The hammering, by bringing the particles of the 
iron nearer together, prefles out the impurides^-and 
jthus completes what was left deBcient by the fufioh* 
This heating and hammering are repeated a number 
of times, till the iron ^h«5 acquired the dcfircd 
degree of perCbdion. Crude iron lofes from a 
jquartcr to a third of its weight by the procefs of 
refining, and is then called forged iron. 

Steel is made by furrounding the bars of iron 
with a compofition of which charcoal is the chief 
and only elTential ingredient, and by keeping diem 
\n an intenfe heat a longer or fhorter dme, accord- 
ing to their thicknefs. They are then taken from 
the furnace, and plunged in cold water. The metal; 
is now fo^nd to be more fiifible than it was before^ 
but to have kfs ductility and foftnefs.* Its tezti|re 
1$ finer; it breaks ihorti its fradlune is alws^ys.grcy, 
and it has gained a fmall increaie of weight. 

With reiped to the chemical ftates of the metal^ 
in the tl^ree forms of caft iron, forged ]ron> an4 
fteel, it appears that they chiefly depend on the 
quantities of plumbago. By folution in acids,) it i^ 
found that cail iron contains a large quantity of 
plijmbago, tb9t i^eel contains fome of it^ but that 
N4 tbf 

i84 Stul. [Book VI. 

tho moft malleable forged iron conuins fcarccly 
any ; it therefore appears, that fteel is in an inter- 
mediate condidon between caft iron and forged 
iron, and that, in making the former into the latter, 
the metal muft pafs through the ftatc of ftccl- In 
fome foreign works they actually manufafkure fted 
by only flopping the procefs of refining at a certain 
point. In diefe manufaftories, however, they make 
life of an ore of uncoiximon purity $ and the iame 
procefs does not fuccecd with ordinary ores, {>ecauie 
die metal obtained from thefe contains other impu- 
rities befides plumbago, which cannot be feparated 
without reducing the iron to its malleable ftate. 

There arc diflPerenccs in the working of iron, 
according to the orqs from which it is obtained, die 
caufes of all of which have not been diicovered. 
The prcfcnce* of phofphoric acid, however, is 
knewn to produce a britdenefs in iron when cold, 
which occafions that fort of iron to be called coU 
Jbort irpn by the workmen. Phofphoric acid is 
chiefly found in iron obtained from bog ores. 

The workmen employed in tempering ftecl 
judge, by the difierent colours it aflumes during the 
operation, of the degree of hardnefs it has acquired. 
That thefe colours may be obferved, fbme part of 
the metal to be tempered fhould be fmooth. 

The changes of colour depend on the calcination 
ofthe iron; for If the contaft of air is prevented by 
the thinneft covering of any oily matter, the cffcft is 
entirely prevented. The colour is firft a pak 
. yelbw i if a piece of ftecl is then ftriicfc off, it wfll 
be very bard.^ If the fteel is left in the fije for a 


Chap- !27-] Caft Steel. !«$ 

longer time, it acquires a deeper yellow and more 
coughneis, with fcarcely any diminution in the de- 
gree of hardneis ; when brought down to the colour 
of watch fprings, it is of the fitteft temper for cut- 
ting wood. Steel> by being heated in this manner^ 
• becomes llicceffively white, yellow, orange, red. 
violet, and laftly blue, which colour remains a con- 
liderable time; but if the heat is raifed it becomes 

Steel, ftrongly heated while in the fire, aflfumes a 
red and fparkling appearance, it next becomes very 
white and dazzling, and then burns with a fenliblc 

Caft fteel is nothing more than fteel refined by 
fufion. During this procefs it throws up icoria^ 
whilft the metallic matter which remains is much 
harder than before, and its texture more uniform. 

Iron is one of the metals which is adtfd on moll: 
powerfully by acids. But not only acids> but alt 
inline fubftances feem to aflfeft it, and even water is 
capable of aAing on it fo as to acquire from ic 
a peculiar tafte. The tendency, indeed, which this 
metal has to combination with other bodies, parti- 
cularly with oxygen, which occafions ruft, renders 
it incapable of permanency, and for this defeft no 
fufficicnt preventative has yet been difcovered 

M * Lavoificr, having expofed iron with water 
in 4 glafs veflfel over mercury, obferved that the 
iron became nifty, and that the Water wasdiminilh- 
ed in quantity. The iron was increafed in.weight, 
and there wa$ a produdion of inflailimable gas, fo 
(hat i^ thjs ea^periment the water was decern- 
* pofcd 


^%6 Green Vitriol. £BookVI. 

pofcd by the iron, even without the prcfence of 

Iron is a£ted on by the vitriolic, miiriatic, and 
nitrous acids, with nearly the f^e phenontiena is 
jtinc. The produds, however, are very difimot 
The folution of iron in the vitriolic acid b of a green 
i:Glour, and by evaporation produces the green 
cryftals, well known under the narnes offal martis, 
green vitriol, and copperas. The green vitriol ufed 
\n commerce is obcained in the following ixianner : 
Pyrites, which are natural combinations of iron and 
fulphur, are expofed to the aftion of the air and 
rain in fhallow pits lined with clay. After having 
been in this fuuation a week or ^ fortnight they 
grow hot and crumble down, and when carefully 
examined are found to contain fmall pryftals. Thcfc 
are diffolved by the rain, and conveyed by pipes into 
a refcrvoir in a houfc, whence the liquor is pumped 
into a boiler made of lead,. This liquor is found 
to have an exccfs of acid, which is remedied by 
calling pieces of iron into it when heated ib as to 
(immer. 3y the addition of the iron a quantity of 
the earth of alum is alfo depofitcd. As the liquor 
cools, the greater part of the fal martis is depofited. 
By theexpofuie of the pyrites to the aftion of air and 
water, the fulphur attrafts the oxygenous principle, 
and is. thus converted into vitriolic acid* Sal mar- 
tis is liable to the watery fufion i when expofed to 
a ilrong heat the aqid begins to exhale, and as it 
exhales the natural coburs of the calx of iron ap- 
pear. It is firft yellow, then orange, then red j if 
\l is ?aJicine<i ;o a greater degree, fcarceljr any of die 


' Chap, ay.] Pru^anBluf. 187 

^ fLcid is left, and the calx retnain$ of a deep purple 
colcufj and is known under the name of colcothar 

^ of vitriol. The nitrous acid afts with fo much vio- 

^ Icnce on iron as to convert it into a brown calx. 

^ With thcr muriatic acid iron afFords pyftals of 
^ livelier green colour than copperas, which will 
not, like copperas, part with the acid by the appli- 
cation of heat. 

All folutions of iron, if expofed to the air, depo- 
fit part of the metal in the form of a calx. Alkaline 
falts precipitate the metal of a bluifh grey colour, 
if the folution 19 frefh, but if long kept, in the form 
of a yellow powder. Mild vegetable alkali lepa* 
rates a yellow calx from the folution of iron in 
the nitrous acid, which foon becomes of a beautiful, 
red orange colour. If the mixture is agitated dur*. 
ing the effervefcenee, the precipitate is re-diflblved 
in much greater quantity than by the pure vegetable, 
alkali. This Iblution is known, by the name of 
Stahl's martial alkaline tindure. 

But the mod remarkable precipitation is that pro-^ 
duced by a fixed alkali prepared with animal inflam-^ 
mable matter. The alkali is treated by mixing i^ 
when dry, with twice its weight of blood, which has 
been indurated and reduced to powder ; (he mix- 
ture is put into a crupible, and a gentle heat ap- 
plied i particukr care muft be taken to ufe the due 
degree of heat, which is known by the difappear-* 
ance of a blue fl^me and fnnoke, which is at firft: 
obfcrvable on the furface. -The matter thus pre* 
pared, being infufcd in water^ afibrds an alkaline 
jfoludon;, which precipitates iron of a deep blue cor^^ 


iS» * PrtilJianBtui. [Book Vl^ 

lour, Specially if a litde muriatic acid is added* 
The cffcmial mgrcdicms of die matter obtained by 
the above procefs feem to be a peculiar matter 
called prufllc acid^ and an alkali. The baie of the 
praflk acid, accordir^ to M. BerthoUet, confifts 
of carbon, hydrogen, and azote* When the alkaE, 
combined with this peculiar acid, is added to a fblo* 
tion of iron, the alkali takes the acid from the iron, 
while the pniftic acid nnitcs with the metal and fidk 
, to the bottom in the form of a blue powder- This 
cffeft of the alkali, thas prepared, is the fbundadon 
of the procefs for obtaining that valuable pigment, 
known by the name of Pruflian blue* , 

Another fmgular, and not Icfs ufefal circumftance, 
in the hiftory of iron is the eflfeft produced on it 
by aftringerw vegetable fubftances. The principle 
of aftringency, which is now found to be a peculiar 
acid, called, in the new nomenclature, gallic acid, 
rcfides in a great number bf vegetable matters,, par- 
ticularly oak galls, tea, &c. According to M. de 
k Methcrie, however, the acid of galls is only a va- 
riety of the colouring principle. Galls are protube- 
lances on the leaves of the oak, occafioned by the 
jmnftore of a particular infeft Any of thefc fub- 
ftances, added to a folution of green viuiol, preci- 
pitjates a fine black fecula, which may be fufpended 
a confidcrable. rime in the fluid by the addition of 
gum arabic. Oak galls are commonly made ufe of 
in diis procefs, which is that of making ink. The 
following proportions of thefe ingredients for making 
ink anfwer very well One ounce of martial vitriol 
p t^rce of powdered galls -, to which one ounce 
■ • " of 

Chap. 27.] Ink 1S9 

of powdered logwood may be added, to render the 
ink more permanent, and oiie ounce of gum arabic 
to fufpend the colouring matter. Let thefe be inftif. 
«d in a quart of water or vinegar for ten days, and 
ihaken occafionaUy,when the ink will be fit for 

The colouring matter of ink Teems to be produced 
from an union of the acid of the galls with (bme 
, part of the ir<Mi in a calciform ftate. A fomll quan- 
tity, of any of the mineral acids dcftroys the colour 
of the ink, by diflblvingthe iron, which was imper« 
feftly precipitated ; and this colour is again reftoned 
by the addition of an alkali, which takes awaf die 
acid. The black fecula of ink is not m«gnetica]$ 
but it may be converted into a brown magnetic 
calx by heat. Ink .becomes blacker by expo- 
Cure to the air, which acidifies more completely the 
principle combined with the iron ; but ancient writ- 
ings become more and more yellow in confequencc 
of the decay of the vegetable matter* Their legibi- 
lity may bereftored by the ufe ofinfufion of galls, or 
gallic acid. The beft method, however, of reftoriqg 
the legibility of ancient writings, confifts in fpieadU 
ing a folution of the PnifTian alkali thinly with sT fea- 
ther over the traces of the letters, and then to touck 
it geixtly, and as nearly upon or over the letters as 
can be done, with a diluted acid, by means of a 
pointed flick. 

The only eflendal ingredients of ink are green 
vitriol, galls, and water. Dr. I^ewis has made 
many ufeful ejcperiments on the proportions df thefe 
ingredients which produce the beft ink. He found 


i5fd Jnk. [Book YI. 

that equal quahtidea of galls and green vitriol pio* 
duced die deepeft cdlour^ but not the moft du- 
rable i he found> that by increafing the quanticjr of 
the galls the colour was rendered more durable ; that 
with three dmes the weight of the galls to ooic of 
the vitriolj the colour was very permanent ; bac 
that if the proportion of g^ was iiicrealed be- 
yond this5 the colour was too weak ; in this cafe 
the wridng was much refrefh^ by waflung it with 
a folution of vitriol. He alfo endeavoured to afixr* 
tain the beft proportion of the fluids to the vitriol 
and the galls. He firft tried water^ and found that 
by confiderably diminifliing the quantity of it the ink 
was more durable^ but too thick for u(e. He found 
that all waters were much the fame > but that whice 
wine and vinegar made a more durable ink s but 
that both thefe were exceeded by a decodion ef 
forty ounces of water to one of logwood,» which of 
itielf gives a permanent red ftain. If the colour 
of the ink fliould fail, that of the logwood will re- 
main^ and it produces^ with ink, a much ftronger 
and blacker colour thai^ ulual$ for the com- 
mon colour of ink is a purplifh blue^ which, 
mixed with red, makes a deep black. He did not 
find any vegetable aftringent equal in all refpeds to 

Mr. Nicholfon dates an objection to the ufe of 
vinegar in the making of ink, which is,' that it ads 
fo ftfongly on the pens that they continually re- 
quire mending. Ink is very apt to become 
mouldy, which is beft remedied by the addition of 
a few cloves reduced to powder i for hot aromatics 


Chap, ay*] TiHning if trdtf. i^t 

arc excellent prcfcrvers of animal and vegetable 

Iron detonates ftrongly ^ith Aitre. It appear* 
to connbine with alkalis by fuficn. The cak o( 
iron combines with earths, aflifts their fiifion, and 
imparts a green colour to the gla6. * Iron has a 
remarkable attraftion for fulphur, and combiaes 
with it either by the action of heat ojr moifturc. 
A mixture of equal parts of iron filings and fulphur, 
made into a pafte with water, becomes hot^ emits 
watry vapours and inflancnnaLle air, in a little time the 
mafs takes fire, and j by attracting the oxygen ofthe 
water, becomes converted into green vitriol, in the 
fame manner as pyrites. Thi§ is the mixture ufcd 
in the produdion of an artificial earthqyake, which 
will be Ipoken of mere fully under the head off 

With refpeft to the relations of iron to the other 
metals, there is litde worthy of note, except its attrac* 
tion for tin, on which is founded the procefs of tinniitg 
iron. In fome countries iron is made into plates^ by 
being repeatedly heated and fubmitted to the aftion 
of a heavy hammer. In England, however, the 
plates are not hammered^ but rolled out to the pro- 
per dimenlions, by being put between two cylinders 
of caft iron^ eafed with fteel. When the iron plates 
have beeil either hammered or rolled to a jproper 
thicknefs, they are fccured with a weak acid, which 
renders their furface perfedly clean m^ bright^ 
and takes ofF! all the ruft, which would pr^vQflt dio 
adhefion of the tin to -their furface.;. they are (heo 
wetted with a ibhitioA offal ammonia(fx.wd{diiDg^ 

I $ t Tinned Iron. [Book Vt 

ed into a vcflel concaining melted tin» the fur&t of 
which is kept covered with pitch or taliow to prt* 
vent its calcination. The tin adheres to each fide 
of the plate, and btimatcly combines with die iron 
to a certain depth, which renders die tinned pistes 
lefs diipoled to harden by being hammered, zsA 
forms an excellent defence for the iron agsunft die 
a&ion of air and moifture. 

Bifhop Watfbn propofes it as a queffion of fonr 
importance, whedier iron of a greater thicknefc 
might not be advantagcoufly tinned ? He dcfifcd a 
workman to break oiF the end of a large pair of 
pincersy which had been long ufed in takiog 
the plates out of the melted tin ; the iron of dr 
pincers feemed to have been penetrated through its 
whole fubftance by the tin ; it was of a white colour, 
and had preferved its malleability. It b ufual to 
cover iron ftirrups, bucklesj and bridle bits, widi 
a coat of tin, by dipping them, after they arc tsaky 
into melted tins and pins, which are made of cop- 
per^wirc, arc whitened, by being boiled for a locg 
time with granulated tin in a ley n^ade -with akn 
and tartar. On thefe circumftances he founds cvo 
queries ; i. Whether the iron bolts, ufed in fiiip- 
building, would be preferved from rufting by being 
long boiled in melnng tin ? a. Whether it would ^ 
poflible to filver iron-plates, by fubftituting mdtcd 
filver for melted tin ? 

It is cuftomary, in fome places, to alloy the tin 
ufed for tinning iron plates with about one-fcven- 
tieth part of its weight of c<^per. Too much cop- 
per ' rcoders the plates of a blackilh hue, but when 


Chap. 27*] MedicM Prepar^imsrf Irm. i^^ 

added to tin io ^ proper proportion^ it enables the 
manu&Aurers to lay on a thinner coat of tin with- 
out injury to the colour. This pra&ice, however, 
is rather of prejudice to the duration of the plates* 
When the tin is bleated to a great degree, the co- 
vering which it imparts to the iron is thinner but 
more even. The plates are apt, from this caufe, to 
have yellow fpots on them \ but this inconvenience 
may be removed by boilipg the plates for two or 
three minutes in lees of wine, or, where they cannoc 
be had, four fmall beer, or other (imilar fluids, may* 
probably be ufed with the fame fuccefs. 

Iron isjuftly confideredas a valuable article of 
the materia medica, and while its utilityjs confi- 
derable, it is entirely free from thofe deleterious and 
debilitating efFcfts which proceed from moft of the 
other metals that are ufed as medicines. The fer- 
rum vitriolatum, or green vitriol, has been ab-eady 
mentioned. The ferri fiibigo is made by merely 
expofing iroa filings to the air, and moiftening them 
with water till they are converted into ruft. The 
ferrum tartarifatum is prepared by mixing one part 
of iron-filings with two of cryftab of tartar moif- 
tened with water, and expofing them to the air for 
eight days, In this preparation the iron is chiefly 
brought to the falinc ftate by means of the acid of 
tartar. The ferrum ammoniacale, or flores mar- 
tiales, is made by mixing one pound of iron filings 
with two of fal ammoniac, and applying a bride 
heat. The fal ammoniac fublimes and carries up 
fo much of the iron as to be changed to a deep 
orange colour. The flores martiales may be made 

Vol. II. O equally 

1 94 Me£cal Prifuraihns rf Jrm. [^Book VL 

equally well with thocolcothar of martial vitriol is 
with the iron«filings« The tinftun fern ammo- 
niacalis, or ammoniacal tindure of iron, is made 
by digefting one pint of proof fpirit of wine wiri» 
four ounces of ferrunti ammoniacaie. The dndura 
ferri nmsriati is prepared by diflblving the ruft of 
iron in the muriatic acid, ajid adding a quantity of 
reftified fpirit of wine. Wine of iron is obtain- 
ed by digefting ruft of iron with Spanilh white wine, 
in the proportion of an ounce to a pint^ for a 


Chap. 28,'] [ I95 ) 

Chap^ XXVIII. 


General fropertiis o/Ttn^^^Greuadated Tin.'^Natural Hifiory of 
Tin^^^Its Union with the Acids. '^^Vfe of Tin in improving ibe 
red Dyes^'^Smoaking Liquor of Libavius.'^Aurum Mufi^vum.^^ 
Comhinatione of Tin with other Metals, •^■^Different Sfecies of 
Piwter.'^Putty.*^ Application of Tin in dying.^^Ufe in Medi* 

TIN, when its furface is frefli, is bright, and with 
rcfped: to whitenefs holds a middle place 
between lead and filven Tin is the lighted of all 
inetals> being only about feven times heavier thari 
water. It produces a cracking noife ipdien it ii 
bent, though it yields eafily. It is very foft, and, 
probably from this caufe, it is fcarcely at all fono-- 
rous. It is confiderably malleable, and may be 
reduced beneath the hammer into laminae thinner 
tlian the leaves of paper (commcmly known by tirt 
name of tin foil) which are of great ufe in fevcratl 
arts, particularly the foiling of looking glafles* Its 
degree of toughnefs is fuch, that a wire of tin of the 
tenth of an inch in diameter fupports a weight of 
forty-nine pounds and an half without breaking. 

Tin is the moft fofible of metals, and melts at a 
little above the heat of 400*, Which is long before it 
becomes red hot. In pafling from the fluid to the 
folid ftate it remains a 9^ort time in an interme-^ 
diate condition^ in: which it has little more cohefion 
O 2 th»a 

1 §6 Natural Hiftory of Ttn. [Book Tl. 

than wet fand, and may be broken by a blow of a 
hammer, or by agitation, into grains. Tin is 
eafily calcinable in an obfcure red heat; it at firft 
forms a grey pellicle ; and in a ftrong heat it cal- 
cines with inflammation into a white powder. The 
calx of tin refifts fufion more than that of any other 
metal; from which property it is ufeful to form aa 
opake white enamel, when mixed with pure glais 
in fufion. 

It is obfervcd by miners, that though rin is the 
lightefl: of the metals, its ores are fome of the hca- 
vieft. Tin is fcldom or never found in the metalb: 
or reguline ftate. The ores are often cryftallizcd, 
and of different colours. Thofe which are of & 
reddifh colour generally contain a large proportion 
of iron. There alfd is a fulphureous tin ore of a 
brilliant colour, fimilar to diat of zinc, or golden, 
like aurum mufivum. The more tranfparent ores 
of tin often contain arfenic, and this is feparated, 
almoft entirely, by repeated roaftings. 

In order to reduce the ores of rin, they are firft 
cleanfed from foreign admixtures by fbrting, pound- 
ing, and waibing. In the fmelting of the ore, care 
is taken to add a larger quantity of fuel than is 
ufual in the revival of other metals, and to avoid a 
greater heat than is necefTary to reduce the ore, in 
order that the \oiz by calcination may be as little as 
poffible. Almoft all the tin ufed in Europe comes 
from Cornwall, which has been famous for its tin 
. iDines from the rcmotefl periods of hiftory. 

Tin is five times as dear as lead, and as a fmall 
quantity of the latter mixed with a large quantity of 


Chap, a 8,] Cmage (f. fin. 197 

the former is with difficulty difcovered, the tempta- 
tion to adijlteratc tin fe great, and the fear of detec- 
tion fmalU Bifliop Watfon ftates> in his Chemical 
Eflays, that in Cornwall the purity of tin is afcer- 
cained, before it is expofed to fale, by what is called 
its coinage. The tin, when fmelted' from the ore, is 
poured into quadrangular moulds of (tone, con- 
taining about three hundred and twenty pounds of 
metal, which, when hardened, is called a block of 
tin ; each block of tin is coined in the following 
manner:— the officers appointed by the duke of 
Cornwall aflay it, by taking ofF a piece of one of 
the under corners of the block, partly by cutting an^ 
partly by breaking, and if well purified, they 
fiamp the face of the block with the impreffion of 
tl^e feal of the duchy, which flamp is a permiffion 
for the owner to fell, and at the lame time an affu- 
rance that the tin fo m.arked has been purpofcly 
examined, and found merchantable *. 

The concentrated vitriolic acid afts on tin with 
the produftion of fulphureous vapours, part of the 
oxygen of the acid5 as is ufual in the folutidns of 
metals in thei^ reguline ftate, being abftraded. 
The acid difliblves about half its weight of tin, but 
not without the affiftance of heat. The folution is 
very cauftic. The nitrous acid is decompofed by 
tin, as it is by moft of the metals, with great rapi- 
dity* The tin is converted into a white cabc, which 
it is very difficult to reduce. M . de Morvcau has 
remarked the formation of a quantity of volatile 

♦ Borlafe'tHi^Ofiy Qf Cowiwall, p. 183. . . 

O 3 alkali 

198 UJe 6f ^iM in dfkg. [Book VL 

alkali during the folution of tin in the nitrous acid. 
This is probably owing to a combination of the 
azote, produced by the acid, with the hydit^cD, 
derived from the dccouipofition of the water con- 
tained in the menftruuxn. The advocates ibr the 
phlogiftic hypothcfis, however, lay, that the hydro- 
gen is the phlogifton of the tin fee at liberty during 
the folution. 

The fuming muriatic acid afts ftrongly on rin, 
inftantly lofing its colour and its property of emit* 
ting fumes. The muriadc acid diflblves more than 
half its weight of tin, and does not let it fall by rc- 
pofc. By evaporation it produces brilliant and very 
regularly formed needles, which (lightly attradfc the 
humidity of the ain The oxygenated mufiadc 
acid diffplves tin very readily, and widiout the 
leaft fenfible effervefccnce* Aqua regia, confiftiAg 
of two parts nitrous and one muriadc acid^ com- 
bines with tin with efFcrvcfcence and the deve- 
lopemcnt of much heat. The folution of tin in 
aqua regis^ is ufed by dyers to heighten the colours 
of cochineal, gum lac, and fome otl^er red tinc- 
tures, from crimfbn to a bright icarle^ in the 
dying of woollens. By firll diffolving tin in the 
marine acid, and then boiling the folution with 
nitrous acid diftilled from manganefe, M. Henn- 
ftsedt has. fucceeded in acidifying tin to fuch ^ de- 
I ^ree as to convert it into an acid \ it bad then. (he 
form of a white powder, foluble in three timfs its 
weight .of water. 

Tin has a ftronger affinity with the muriatic add 
than mercury has, m^ decompofes the corrofive 


k Chap. a8.] Pmwf Uqucr (f Uhmus. i j7 

> mercurial fublimate. To tSe& this, the tite » 

t - firft divided by the addition of a fmali portion of 

E mercury i equal parts of dm amalgaAi and the cor- 

K rofive fublinute are triturated together^ and the 

mixture expofed to diftiUation in' a gla& retort with 

a very gende heat* A colourlefs liquor firfl: pafles 

over, and is followed by a thick white vapour. 

The vapour becomes, condenied into a tranfpareni 

f fluid, which continually emits a thicki white, and 

[ very abundant fume. It is called the fuming K« 

t quor of Libavius, and is a combination of the 

. muriadc acid and tin. The imell of this fluid i$ 

I very penetrating, and excites coughing. The vapours 

I are not vifible without contafl of air, and ieem to 

; confift of a peculiar gas, which is decompofable hj 

{ air, and which then depofits the calx of dn in the 

\ fame manner as the hepadc gas of Bergman depofits 

fulphur by the conca£k of air. M. de Fourcroy 

I propo&s it as a query, whether this elaftic fluid is 

a coropofldon of the oxygenated muriadc acid and* 

t'ui ? When water is added to this fuming liquor 

in a certain quantity, it becomes folid, and ceafes to 

emit fumes. It is found that this concrete fubftance, 

when rendered fluid by an increaie of temperature, 

is capable oi diflblving more tin without the efcape 

of hydrogen gas. Hence it appears that the 

oxygen neceflajy for the folution of this additional 

quantity of metal is not derived from the water 

but the acidj and that the acid tx> impart it muft 

be IB an oxygenattd ftaie. The experiments of M. 

Adet have thrown much light on the nature of th« 

O 4 fuming 

200 Jurum Mufrjunii Pewter^ l^c. [Book VI. 

faming liquor of Libavius, and are publifticd in die 
Annales dc Chcmie. ' 

Tin is capable of decompofmg all the vitriolic 
neutral faks. Tin has a confiderable attraftion for 
iulphur^ and cafily unites with if, when in a ftate of 
fufion, into a black mafs. Aurum mufivum is a 
combination of tin and fulphur, obtained by a parti- 
cular procefs. Arfenic cannot eafily be united to tii^ 
on account of the volatility of the former metal 
Cobalt unites by fufion with tin, and forms an alloy 
in fmall clofe grains of a light violet colour. Bif- 
muth in fmall quantities, as well as zinc, im{:art a 
finmnefs and whitenefs to tin. Mercury diHblves 
tin with great facility, and in all proportions. 

The ufes of tin are very numerous. It is applied 
to many purpofcs in the arts. Its amalgam with 
quickfilver or mercury is applied to (ilver looking- 
glaflcs. The ufc of tin in covering plates of iron 
has been already (pecified; and it is alfo employed 
in lining the infide of copper veflels. It enters into 
the compofitioh of bronze and bell metal. It is 
the chief ingredient in the compofition of pewter. 
Pewter confifts of tin united to fmall portions of 
other metallic fubftances, fuch as lead, zinc, biA 
muth, and antimony. We have three forts of 
pewter in common ufe; they are diftinguilhed 
by the names of plate; trifle i ley. The plate 
pewter is ufed for plates and dilhes; the trifle 
chiefly for ale pints, quarts, &c. and the ley- 
metal for wine meafures and other coarfer ufes. 
Our very bcft pewter is faid to confifl: of one hun- 
dred parts of tin to from ten to feventeen of anti- 


Chap. a8.] VJes of ^in in Arts. and MedUine. aoi 

mony. To this compofition the French add a little 
copper. In general the lighted pewter is the belt. 
The inferior kinds arc heavier and fofter, from a 
quantity of lead with which they are adulterated. 
Putty is prepared from tho white calx of tin. The 
iblution of tin in aqua regia has been already men- 
tioned as ufefol in dying. When it is mixed in the 
dyer's bath it forms a precipitate, which carries 
down the colouring matter, and depofits it on the ' 
ftuff which is to be dyed fcarlet. The operation of 
tinning copper will be afterwards defcribed. The 
powder of tin has been ufed as a remedy againft 
worms in large dofes, and therefore the fcruplcs 
which have been entertained againft the ufe of 
veffcls lined with tin muft be wholly without foun- 
dation. Tin has been analized by many chemills, 
with a view to difcover the quantity of arfenic con- 
tained in it. The refults of thefe experiments have 
been by no means uniform. The largeft propor- 
tion, however,' which has been detefted in any tin 
ufed in commerce, is a grain in an ounce, or one 
five hundred and feventy-fixth part of the com- 
pound ; but more frequently no arfenic whatever, 
has been difcovcred. 


[ ao2 3 [Book VI. 

Chap. XXIX. 


G^mriJ PreferMs ff Leai.^Rei Lead.^Utbarg9.'-^Naiwrgi 
Uiftoty of Lead. — Smelting Lead Ores.^Vmon with Actdi^^ 
Plumbum Corneum, — White Lead; hew ma^.^'^agar af 
lead.'-Unum ^itb ether Metals. ^Commea Selder.'-'^JJes 4 
l^ad.'^Great Danger from leaden VeJleh^^^Devonfifire Colic. 
m^Meaus of detecting Lead in Liquon^-^Midical Ujes of Lead. 
-^AJfes of its Calces in the Arts. 

THE appearance of this metal is well knows. 
It is fo fofc as to be cut with a knife without 
much difficulty. It is neither fonorous nor, daftic. 
It has very little tenacity, and therefore cannot be 
drawn into fine wire. It fpreads cafily under the 
hammer, but cannot be extended into very thin 
leaves like gold, filver, and tin. Its fpe;cific gravity 
is rather greater than that of filver, being eleven 
times heavier than water, and it is exceeded in this 
rcfpcft by only three metals, gold, platina, and 
mercury. Lead melts at the five hundred and 
fortieth degree of Fahrenheit's thermometer, before 
it becomes red hot. 

Lead, like tin, at a certain point betweep its fluid 
and folid ftates, poflefies very litde cohefion, and 
may be feparated by a fmart , blow with a hammer 
into grains, which are ufed in afiaying the ores of 
gold and filver. 


Chap. 29.] Rid JUad. 5203 

Iwicadj foon afcer it is melted> acquires a filai 
qff its furfi^ce, which prefents in fucceflion a yarictf 
of. colours. This film becomes thicker, and of a 
grey colour, by the continuance of the calcination, 
and is then called plumbum uftum. If the firft 
pellicle is removed, another is quickly formed, and 
in this way almoft the whole of the lead may be 
converted into a greyifh powder tinged with green 
and yellow. This powder, being ground in a mill 
.and walhcd, becomes of a more yellow colour. 
By further expofure to a moderate heat, aflifted by 
the reverberation of the flame of the fuel on the fur- 
face of this calx, ic gradually affumes an orange, 
and then a. bright red colour, and is thus, in about 
forty-eight hours, converted into the fubftance 
called minium, or red lead. If lead is, in the phrafe 
of the chemifts, urged with a more violent and 
fudden heat, the appearances which it exhibits are 
different. It is firft converted into a flaky fubftance, 
called litharge, which, by the procefs juft defcribed, 
may be converted into minium, but which, by an 
increafe of heat, becomes fluid, and ads fo power- 
fully as a folvent on earthy fubftances as quickly to 
make its way through ordinary crucibles. 

All thefe calces of lead may be eafily reduced to 
the metallic ftate, by melting them in contaft with 
inilammable fubftances. In calcining and reducing 
fixty hundred weight of lead, there is found to be a 
lofs of eight hundred. This lofs was explained by 
the old chemifts on the fuppofition of the efcape of 
a volatile fubftance called by them mercurial earth, 
but which was never proved to have any exiftence. 


a04 Natural Hiftcry of Lead. [Book Vi 

The l<rfs, however, ought to be attributed in foar 
meafure to thcevaporationof part of the lead irieU 
and partly to the imperfcftion of the procefs^ask 
]k feldom performed fo accurately as to reduce dx 
whole of the calx. 

Lead is very rarely found qativc. It is fiwnc. 
times found in the form of a calx, called native cp- 
rufe, or lead ochre, or in that of lead {par of varioa 
colours, and which are in general either rhomixMcU 
or cubical^ Lead combined with fulphur is cafai 
galena, which is compofcd in general of hsm 
which have nearly the colour and afpeftoflol 
but are more briHiant, and very brittle. A grot 
variety of thefe ores have been difcovcred, whidi 
will not be neceflUry to enumerate. Lead, in fomc 
inftances, has been found combined with variw 
acids ; the vitriolic, the phofphoric, the carboKc; 
and the arfenical. The ores of lead very commodj 
contain filver, and fometimes antimony. 

In fmelting lead ores the fulphur is diffipatedfa 
want of a proper apparatus for collefting it. Ac- 
cording to bilhop Watfon's experiments, the Dcrf)j- 
Ihirc lead ores contain in general from one-fevcntk 
to one-eighth part of their weight of fulphur. OtiI 
of the chief circumftances to be attended to in tbc 
fmclcing of lead ores, particularly fuch as conoifl 
much fulphur, is to keep them for fome hours in* 
moderate heat, by which that fubftance may fe 
gradually diflipated. After this the fire mull be 
raifed to fufe the mafs completely, by which the 
metal flows through the fooriae, and is coUeded m 
the cavity at the bottom of the furnace. Tte 

jChapw29-3 IVhite-Lead'. loj 

fcori^ being then thickened by the addition of lime, 
fo that they may be raked a fide, a ftoppcf is drawn 
out ai)d the lead fufFered to flow into an iron pot, 
whence it is laded into nnK)ulds, which form 4t into 
the mafles called pigs of lead. 
' Lead is foluble in the concentrated vitriolic acid, 
by the afliftance of heat only.' The lead then forms, 
with the vitriolic acid, a fubftance fcarcely foluble in 
water. It feems to have a peculiar affinity with 
, this acidr and leaves all others to combine with it,^ 
which is not the cafe with the other metals. 

The nitrous acid afts ftrongly on lead. When 
the acid is concentrated, it corrodes the lead into a 
white calxi but if it is confidcrably diluted, it dif* 
folvcs the lead. This folution does not afford a 
precipitate on the addition of water. Its cryftals, 
cbtabed by cooling, are of an opake white. This 
fait decrepitates in the fire, and melts with a yellow- 
ilh flame when laid on ignited charcoal. The dalx, 
which is at firft yellow, is quickly reduced into 
globules of lead. The vitriolic acid added to this 
folution combines with the metal, and forms a pre- 
cipitation. The marine acid, in the fame manner, 
fcizes the lead, and form's a combination, which, if 
expofed to heat, melts into a mafs of a brown 
colour, called plumbum corneum, from fome rc- 
fcimblance to the combination of the fame acid with 
filver, called argentum corneum. 

The. acetous acid, or vinegar, a<Sts on lead,.parti- 
cularly when applied to It in fteam, in which procels 
the aftioi|i of the air probably affifts that of the acid. 
To procure white lead, ihects of lead are rolled up 

* fpirally. 

lo6 FalalEffe£Isc/ff^eLeadfrarks.lBock^\ 

ipirally ib as to leave the (pace of about an indi 
between each coil> and placed vertically in eardiea 
pots, which have fome good vinegar at the bottoiB. 
The pots are covered> and expofed to a gentle heat 
for a confiderable time by fubrounding them with 
horfe-dung. The (teams of the vinegar circdase 
in the veflel, and attach themfelves to the (iirike 
of the lead, converting it into white flakes, whidi 
come off when the lead is uncoiled. Xhe remaia- 
ing lead is again expofed to the fteams of the vine- 
gar, till another cruft is formed, and the procefsis 
repeated till its whole fbbftance is converted ioto 
the white flaky matter called cerufc, or whic 

Such are the deleterious efFeds of lead, when 
taken into the human body, that die wretched la- 
bourers in white lead works are feldom known to 
lurvive more than three years, when they expire in 
excruciating pain from the Devonfhire colic, lofcdnt 
entire ufe of their limbs, or gradually pine away by % 
waiting marafmus. In a well regulated commu- 
nity fuch works ought to be entirely prohilHted, or 
at leaft only carried on by the worft of felons, whofe 
lives would be otherwife forfeited. 

Lead, after being thus reduced to the flatecf 
cerufe by the fumes of the acetous acid, may be 
eafily diflblved in the fame acid in a fluid Hate, aod 
the faline matter thus formed, is then called, from 
its fweet but aflringent tafte, fugar of lead. 

To have this fait of lead in the form of tnuifpa- 

rent cryftals, it is neceflary to ufe much acid; ^ 

there is not a redundancy of acid, moft of the aji- 

a tals 

Chap. 19.] Sugar rf LeatL ao7 

tals are fmall and mealy. This may be remedied 
by diflblving them again in diftilled vinegar> and 
repeating the cryftallizarion., In this manner fo 
much of the acid may be united to the metal as to 
change the appearance of the lalt to that of an #ily 
fluid. This nnietallic falt> like others^ may be 
decompofed by an alkali. In all thefe cafes the 
precipitates of lead are white> but the calces arc 

The faccharum iaturni> or iugar of lead^ may be de«9 
compofed by heat alone^fbr, when expofed to a gi»* 
dual heat» the acid rifes in a very concentrated fttite* 
This procels is attended with the remarkable pheno-^ 
menoa of the produftion of a quantity of ardent 
ipirit. , By the phlogiftic hypothefis this fad admit- 
ted of explanation, by fuppofing that the principle 
of inflammability of the metal combined itfelf with a 
portion of Vater, contained in the acetous acid, and, 
thus formed alcohol, or fpirit. Upon M. Lavoifier*s 
principles, however, it may be much better account* 
ed for. It has been proved by him, that alcohol is a 
combination of hydrogen, charcoal> and a fmali 
I quantity of oxygen. Now all thefe principles exifl: 
in vinegar, the bafis of which is hydrogen and 
ch^coal, brought to the flate of an acid by their 
union with a large proportion of oxygen. The 
chief difference, therefore, between vinegar and 
alcohol is, that the former contains much more 
oxygen. As part of the oxygen, however, after 
this operation, is (till retained by the lead, which is 
not reduced to its metallic form» it is very natural 


€o8 LeadSMer. [BookVT. 

to fuppofe that part of the fluid which paflesover 
ihouldbe reduced to the ftate of alcohol. 

Nitre, heated with lead, calcines it into a ydkw 
iiibftance, but without producing deflagradoo. Sal 
ammoniac and common fait are decompo&d by be- 
ing heated wich the calces of this metal, but the neu- 
tral iaits, in general, are not a£ted on by it» Sulphur 
readily diflblves it by the affiftance of heat, aixlpio- 
duces a brittle compound of a deep grey cok&r 
and brilliant appearance* Phofphorus may be 
united with lead, and forms with it a malleable and 
foft compound, not very different in appearance 
from lead it(elf . 

Lead combines with bifmuth, and affords ameol 
of a fine clofe grain, which is very britde. The 
alloy of lead with arfenic has not been examkied 
Nickel, manganefe, cobalt, and zinc, do not unite 
with lead by fufion. With antimony it fonnsa 
britde alloy, with fome brilliant facets. Mcrciny 
diflblves lead with the greateft facilit}% Lead 
unices very cafily with tin. Two parts of Icadwidi 
. one of tin form an alloy more fufible than cither 
of the metals taken feparately, and which is, thcI^ 
fore, ufed by plumbers as a folder. 

Lead is ufed for a great number of economical pur* 
poles. Leaden teffek, however, arc very apt id com- 
municate injurious properties to all fluids whichare 
kept in them for any length of rime, and fhould wholly 
be rcjefted in the management of fuch fluids as con- 
tain an acid capable of a£ting immediately on tht 
metal, and of diflblving fo much as irreparably to 


! Chap, 29.] Devmjbirt^olic. 109 

i injure the conftitutions of perfons who are in the 
habit of ufing them. Inftances in which lead re« 
I ccived into the body has produced the lingering 
I and painful diforder called the painter's colic, or 
! the colic of Poitou, arc too numerous to leave any 
: queftion as to the pernicious cfFefts of this metaL 
The liquors in which an admixture of lead is moft 
to be apprehended are, cyder, wines, and rum. Irt 
Devonftiire, from the great ufe of cyder, and 
the improper methods of making it, by which, 
either through cveleflhcfs or defign, lead becomes 
diffolved in it, the diforder above mentioned prevails 
fo much, as to have obtained the name of the De- 
vonlhire colic. 

It is unfortunately the cafe, that lead diflblved jii 
vinous liquors is capable of imparting a rich and 
agreable flavour to them, and even of reftoring 
them after they have become confiderably acidu- 
lated. The temptation to ufe lead, therefore, in this 
way is great; and fo long as dealers are ignorant of 
the pernicious effects of this metal, or want ho- 
nefty to prefer the fafety of their cuf^omers to their 
own profit, there is no reafon to hope that the ha- 
bit of occafionally ufing it will be aboliflied. The 
adulterating of wines in this manner was {o com^ 
ition a few years ago in France, that it was unfafe 
for flrangers to ufe the wines which were fold at their 
inns. It is very defirable to be furnifhcd with the 
means of detecting this pernicious ingredient, and 
the following are recommended by an author, whole 
ipecylations even on the moft common fubjeds htfvt 
ever been dire^ed to the public good^ and are al- 
Vol.. IL P waya 

fi lO Means ofJi/ccvmngLeadin Liquors, ^Book VL 

3/eays produAive of puWic advantage * : Boil toge- 
ther, in a pint of water, an ounce of quick lime and 
half an ounce of flowers of brimftone, and whentbe 
liquor, which will be of a yellow colour^ is cold, 
pour it into a botde, cork it up, and refenre it 
for ufe. A few drops of this liquor, being let fill 
into a glafs of wine or cyder containing lead, wiB 
change the whole into a colour more or icfs brown, 
according to the quantity of lead which it contaios; 
if the wine is wholly free from lead, it will be ren- 
dered in fome meafure turbid by the liquor, bat 
the colour will be rather a dirty white than a blackifii 

In general, a folution of common liver of fiiptof 
win precipitate the lead, but unfortunately iron as 
well M lead is precipitated by both thcfe tefts, and 
it is ikid that many honeft wine merchants hive beca 
ruined by this means, by having unjuftly ftiko 
under the fufpicion of adulterating their wines widi 
lead. M. Hannemann has publiflied a paper in tk 
Joornal de Phyiique, in which he afiures us, th^t dx 
following liquor, whilft it does not precipitate ipoOi 
wiU preqipitate lead and cqp^r of a black coloor, 
and arfenic ot an orange. Mix equal pants d 
oyfter iheUs and crude fulphur in fine powder, and 

• Bifliop Watfon. This excellent and truly rcfpcdabk 
author, this great ornament of the Englifli church, will, I ^' 
tarmyfelfy forgive the very free and frequent nfc 1 havcflai 
0f Ms xncemparabic Eflays. He has ^ver been 
** Mihi tnagnos Apollo." 

*' My guide, philofopher " 

and, if I was not afraid of prefuming too far, I would add tk 
coiicluHt)!! of that well known line. 


Ghap. ^9,] E9CteHfro^EffiEt4 (ftbePoifrn of Lead. 21% 

put them into a crucible ; apply a briik fir^ m aa 
air furaace, fo as to make the crucible of a whit^ 
heat for about fifteen minutes. The ma&y when 
cold and powdered, fhould be kept in a bpttle w^JJ 
corked. To prepare the liquor, put one hi^ndre4 
and twenty grains of this powder, and one hyndred 
and eighty grains of creaoi of tartar, into a very 
ftrong botde, fill it with water, ]et it boil for a^ 
hour, and then cool. Cork the bottle, and frequents 
ly Ihake up the ingredients. After it h^ ftcio^ 
for fome hours to fetde, pour off the clear liquor^ 
and put it into little bottles, 'which contain about 
an ounce,' having previoufly dropped- into each 
twenty drpps of marine acid. Cork tl>eni clofe 
by means of wax mixed with a litde turpen- 
tine. One part of this liquor, mixed with three parts 
of the wine fuppofed to ?ontaiq noxious metal- 
lic particles, will 4ifpover, by a black precipitate 
the frnalleft particle of le^d, copper, &c. biif will 
not affcft the iron contained in it. Pure wiqes ^p 
not difcoloured by the addition of this liquor. 

The deleterious effe(5h pf lead are not confined cp 
^ its aftion on the ftpipach. Men who iy9rk in tl^e 
manyfaftories (or the different pr.ep^ratipfls oflpafi 
9K liable to complaints vpry fiijjili^r ?q, thpfe wfto 
drink liquors containing lead. Painter^ ^xlp ^ 
liable to this complaint, from the lead contained in 
pdnt, that it has obtained, oq (his account, the 
name of the painter's colic. 

Lead is the moft powerful article in the materia 

medica in rcflraining hemorrhages and exceffivc 

difchargcsi but its ufe is fp dan^roy? th^t it; is hot 

P 2 very 

ft 1 2 Goulartts EfntraBy ISc. [Book VI. 

very often employed internally by phylicians. The 
preparations of lead are, however, highly beneficial, 
without being generally dangerous, as ingredicos 
in plafters and other external applications, partka- 
larly in the well known Goulard's cxtrad. 

The calces of lead are ufed in making to 
kinds of glafs, of which they increafc the folidity, vh 
to which they impart a kind of unftuofity which fc 
ihem for being cut and polifhed with Icfs danger of 
breaking. Lead enters particularly into the coid- 
pofition of flint glafs, and the compofirions calkd 
paftcs, or artificial gems. The chief dcfcd of ffi* 
glais is, that it is apt to be of unequal denfity,wiiicli 
renders it difficult to find pieces of any confidcnbk 
dimenfions free from ftriae. Litharge is alfo on- 
ployed by potters for glazing their ware. 

The ufes of red and white lead, as pigmcnis, 
arc well known The common red wafers arc co- 
loured with red lead, as may be cafily fecn by hold- 
ing one of them in the flame of a candle, whcnikc 
lead will be reduced, and appear in litdc globule; 
thcfe wafers fliould, therefore, never be left iutkc 
way of childreq, as they may be induced to fwallfl» 
them, and may confequently fubjeft thcmfdvcsto 
all the ill efiefts arifing from this fatal poifon. ThP 
bcft red wafers arc coloured with vermilion- 


Chap. 30.] £ a»3 3 


Chap. XXX. 


General Properties jof Copper.-^Its Natwral Hiftory.'^^Turqmfi 
Gem.'^Smelting emd refining tf Cofper^^Antique Staiuu 
preferred by the Green Rufij^^Union tviti JiciJs.m^Blut 
FitrioL'-^Colourmg of Gunsj'^Cuprum JmmoniacMm.'^Verili^ 
gris^^-^Union nvith Metals,^^Wbite Copper^^^P^nchheckj^-^nn 
Metal.^-^BeU Metal^-^Metal of ancient Statues j^Bronxi.'^ 
Speculums of Refle^ing Telefcopes. — Pot Metal, — Tinning of 

COPPER is a metal of a peculiar red colour, 
and when its fur&ce is frclh and clean it has a 
confiderable degree of fplendor. It is hard, due- ' 
tile, and malleable to a confiderable degree, and 
remarkably fonorous. It has a peculiar and unplea- 
fant fmell, particularly when rubbed. Its talle \% 
ilyptic and naufeous. Its tenacity is fuch, that a 
copper wire of one tenth of an inch in diameter is 
capa^)le of fupporting a weight of about three hun- 
dred pounds. Its firadure exhibits the appearance 
<)f frnall grains. Its gravity is about nine times 
that of water. 

Copper has a great degree of ftrength and rigi* 
dity, approaching to that of iron. It is not in- 
flammable like iron, and is therefore ufed in gun- 
powder works,, inftead of that metaL It does not 
admit, like iron, of being welded, but this defeft is 
compenfated by its greater fufibility, by which it 

P 3 niajr 

214 Turquoi/e Stone* [Book VI. 

may be always formed into the defircd Ihapc. It 
requires for its flifion about the fame heat as gold 
and filver. When in fiifion, for which it requires 
a ftrong white heat, it appears of a blueifli green 
colour, which arifes from a flaifie of that colour on 
its furface. By a very violent heat it boils, and b 
volatized partly in the metallic ftate. Copper, ia i 
heat far lefs than is fufficicnt to melt it, becomes- 
calcined at its furface, and exhibits various cdouis. 
In a greater heat thaA is fufficient to produce tizis 
cffed, its furface is converted into thin fcales, which 
may be eafily fcrap^ oflF. 

Copper is fometimes found native, having 4e 
metallic fplendour, the malleability, and all the 
properties of ordinary copper. It has fomctimcs 
the foroa of. plates, fometimes that of fibres or 
branches, and is fometimes cryfl-allized. Copper, 
in its metallic ftate, is fometimes found depofitcdon 
ores of iron, in which cafe it muft be confidcrcd as 
having been fepaiated from native vitriol of copper 
by the fuperior attraftion of iron for the vicrioiic 
acid. The native folutions of copper often dcpoft 
that metal in a calcined fl:ate in beds of calcareous 
earth. The turquoife fl:one is the tooth of an 
animal, penetrated with the blue calx of copper. 
Copper is ^generally found, however, contained in 
ores. Thcfe are frequently mineralized by fuljAur. 
What are improperly called the vitreous ores of 
copper are of this kind i they are brown, red, affJ 
grey, and thefe colours arc frequently mixed wiA a 
greenifh or violet tinge. Thefe melt cafilyi ^ 
very ponderous, may be fcratched or even cutinA 


Chap. 3o»] Natural HJiorj of Copper.. ax^ 

a • knife, and are very rich in metal, as an hundred 
pounds of them ufually yields from eighty to ninety 
of copper. The azure copper ore differs from the 
former chiefly in containing a confidcrable quantity 
of iron. The grey copper ores, which have not 
much fplendor, confilb of copper, fulphur, arfc- 
nic, and fome iron. What are called copper py- 
rites contain in reality more iron than copper, but ' 
yield enough of the latter metal to anfwer the ex- 
pence of working them ; diey are generally of a 
yellow and brilliant afpeft. Copper is alfo, in fome 
Ipccimens, found united with flate, pitcoal, zinc, and 

Copper is feparatcd from its ores by different 
proceffes, according to the nature of thofe ores. If 
they contain much fulphur, after being pounded 
and walhed, they are roafted in the open air to 
difpel the fulphur, which in a greiat meafurc fup- 
plics. the want of other fuel. The ore is afterwards 
roafted once or twice more with wood, and is 
melted in an open fire into a mafs called a mat of 
copper. In this ftate it ftill contains a large quan- 
tity of fulphur, which the workmen continue to 
expel by repeated roaftings and fufions, till the 
metal acquires a certain degree qf purity, and is 
called black copper, which is fomewhat malleablcf 
b\^t ftill contains fulphur, iron, and generally fome 
other impurities. In order tp get entirely rid of 
thefe, the copper is haftily fufcd with three times 
its weight of lead. The lead unites with the 
copper and expels the iron, and the imperfcft 
metals, which happen to be mixed with the copper, 

P4 arc 

tt6 SmebtMg and refining rfC^fpiTy ISc. ^Book VL 

are expelled by cupcUation. The copper is a&r- 
wards refined, by keepmg it heated in crucibles fiv 
a confiderable time, fb that it may throw up all the 
foreign fubftances it ftill contains in the fi>nn of 
fcorias. It is examined, from time to time^ by im- 
merGng iron rods in it, which become coloured 
with a fmall quantity of copper, and its purity is 
judged of by the brilliant rcdnefs of thele ipcd- 

Copper is not (b eafily a£bed on by the za as 
iron. In fituations, however, where it b expoiU 
to the adion of moift air, it becomes gradually co- 
vered with a green ruft or calx, which is fapid aod 
foluble in water. This ruft never penetrates into 
the fubftance of copper, but feems rather to contii- 
bute to the prefervation of its internal parts^ as mzf 
be feen in antique medals and (latues of diis metal 

Copper does not unite with earthy matters i 
its calx, however, promotes their fufion, and fonm 
with them glades of a deep brown. Cauftic fixed 
alkalies, digefted in the cold with filings of copper^ 
afTume, after a time, a light blue colour, the C(^ 
per bccotning covered with a powder of thciinic 
colour. Copper, treated in the fame manner with 
volatile alkali, produces, in a few hours, a deep and 
moft beautiful blue^ the quantity of copper taken 
up being very inconliderable. From the ftrong 
blue colour produced by the adion of copper zsA 
. volatile alkali, they become excellent telb of the 
prefence of each other in any body, fluid or folii 

Copper is in general eafily adfced on by adds. 
The vitriolic acid, however, does not aft on it 


Chup. 30.] Blu^ Vitriol, &?r, 117 

unlds concentrated and aflifted by heat; it then 
corrodes the copper into a brown matter of a thick 
confidence, which, by the addition of water, affords 
a folution of a deep blue colour. If this folution is 
evaporated to a certain point, and fuffered to cool, 
long rhomljoidal cryftals are afforded of a deep 
blue colour, called vitriolated copper, or blue vi- 
triol; it appears thercfpre that^vitriolic acid forms, 
with iron, green cryftals; with zinc, white cryftals; 
and with copper, blue cryftals. 

Copper may be obtained from the folution of 
blue vitriol, by dipping into it pieces of iron. The 
vitriolic acid diffolves the iron in preference to the 
copper, and depofits the latter, in its metallic form, 
on the furface of the iron. Upon this circumftancc 
is founded the procefs for browning fowling pieces. 
T^he barrels are moiftened with a folution of blue 
vitriol, which. diflblves the iron to a very inconfi-^ 
derable depth, and depofits in its place a thin lamina 
of copper. 

Blue vitriol has a ftrong ftyptic tafte, and is in 
fome degree cauftic. Expofed to heat it parts 
with its water of cryftallization, melts, and becomes 
of ^ pale blue colour. A ftrong heat ik required 
to feparate from it the vitriolic acid, which adheres 
more firmly to copper than iron. Blue vitriol is 
decompofed by niagnefia and by lime. If the mild^ 
vegetable alkali is poured into a folution of blue . 
vitriol, a precipitate is formed of a pale blue co- 
lour, which, however, becomes green by expo« 
fure to air: in this experiment no effervefcencc 
takes place, and we may therefore conclude that 


ftiS Beautiful Green Taint. [Book VI, 

die carbomc add of the mild alkali unites withib 
calx of copper. Volatile alkali precipitates (k 
Iblution of blue vitriol, in the fame manner, of i 
blueifli white colour i but the mixture very fooD 
' becomes of a deep blue colour, which happens 
from the alkali re-diflblving the precipitate. Inorfa 
to obtain the cuprum ammoniacum, whicb has beer 
recommended as a remedy for epilepfy, add roh- 
tile alkali till the whole precipitate o( copper i 
rediffolved, then fet the folution before a fireina 
flat veflel, and let it gradually evaporate, whidi 
ihould be done with a heat not exceeding that d 
the human body; the matter which remains at it 
bottom, in the form ofacruft, muft be rvbhedin 
mortar, that it may be intimately mixed. 

The blue vitriol of the (hops is made bymcaos 
of the aftion of fulphur upon copper; thefe ait 
gently calcined together; the fulphur attrafb the 
oxygen of the atmolphere, and unites with the cqp- 
per into a foluble powder, which is afterwank 
cryftallized into blue vitriol. 

A beautiful green paint may b^ precipitatca 
from blue vitriol, by means of white arfcnic dif- 
folved in water together with vegetable alkali. 

The nitrous acid diflblves copper with ^ 
rapidity, without the afliftancc of heat, vnth ox 
produftion of a large quantity of nitrous g^- 
Part of the metal falls down in the form of a calx, 
and the filtrated folution, which is of a muchdcqjcf 
blue colour than the vitriolic folution, affords 071- 
tals by flow evaporation^ This fait is more cono- 
five thajn vitriolated copper j it fo powcrfolty ^' 

Chap. 30.] jlBmofVigttahle Acids m Copper. I19 

trafts the humidity of the atmofphcrc that it dc* 
liqucfces, unlcfs kept in clofe veflcls or^in a vcrj^ 
dry place. When melted in a crucible it emits 
large quantities of nitrous vapour and becomes 
brown, in which date it is merely a calx of copper. 
In a dry and hot air this fak becomes covered with 
a green efflorcfcence. It detonates flighdy on burn- . 
ing coals. 

The muriatic acid afts wth great difikulty on 
copper in ks metallic flfate, but difS^^s its calces 
with confidcfable rapidity. This may be eafily 
accounted for from the ftrong attraction which the 
bafe of the muriatic acid has for oxygen, fo that it 
will not part with any of it to oxygenate the metal, ^ 
and no metal is foluble in acids without being flrft 
oxygeiiated. When, however> the metal has been 
prepared for folution by an union with oxygen, that 
is by being calcined, the acid then diffolves it, and 
' adheres very clofely, fo that it is with great diffi* 
culty feparated by heat. The muriatic folution of 
copper is of an agreeable green colour, and affords 
cryftals of the fame, and in this particular differs 
remarkably from the vitriolic and nitrous combi- 
nations of copper, which are of a deep blue. 

The vegetable acids difTolve copper when cal- 
cined, but fcarcely aft on it in its metallic ftate. Ic 
is a curious circumfbnce, which has never been* 
fofficiendy explained, that vegetable acids aft more 
powerfully on copper when cold than when they are 
heated. Thus pickles, or even lemon juice, may be 
boiled in clean copper veflels without danger; and 
yet, if left for a few hours, when cold, in copper vef-^ 
3C , ' fels. 

iao Preeffs of preparing Ver£gris. [Book VI. 

ttlsy thejr zxt apt to contrad a metallic impregnatioQ 
Efficient to produce dangerous efiedb. T^his lad 
bas by feme chemifts been attributed to the fteazxis 
of the boiling fluid keeping off the air, which is 
thought to aiCft the action of the acids. 

Verdigris is a very beautiful green ruft or calx of 
copper, niuch ufed by painters^ and prepared in 
large quantities near Mpntpelier in France. The 
procefs for making verdigris was thus defcribed bf 
M. Monnct, of the Royal Society of Montpelier. 
about the year 1750. Vine flalks, wdl dried in 
the fun, are fteepcd, during eight days, in ftrocg 
wine, and afterwards drained; they are then put 
into earthern pOts> and wine is poured upon them; 
the pots are kept carefully covered. The wine 
undergoes the acetous fermentation, which in fiim- 
mcr is finiflied in feven or eight days, but requires 
a longer time in winter, though this operation is 
always performed in cellars. When the fermenta- 
tion is fufficiendy advanced, which may be known 
by obferving the inner furface of the lids of the 
pots, which, during the progrefs of the fermentation, 
are continually wet by the moifture of the rifing va- 
pours, the ftalks are to be taken out of the pots. 
The ftalks are by this method impregnated with all 
the acid of the wine, and the remaining liquor is 
only a very weak vinegar. The ftalks arc now 
dndned fome time in balkets, and layers of them 
are put into earthern pots with plates of Swedilh 
copper, fo difpofed that each plate may reft on and 
be covered with layers of ftalks. The pots are co- 
rered with lidsj and the copper is thus left expoied 


Chap. 30.] Detonation cf Copper. aai 

to the aftion of the vinegar for three or four days 
or more, in which time the plates become covered 
with verdigris. The plates arc then taker! out of 
the pots, and left in the cellar three or four days, 
at the end of which time they are to be moiftened 
with water, or fome of the weak vinegar above 
mentioned, and left to dry. When this moiftening 
and drying of the plates has been repeated three 
times, the verdigris will be found to have increafed 
confiderably in quantity, and*it may then be fcrapcd 
off for lale. 

A folution or erofion of copper may be obtained 
by employing ordinary vinegar inltead of wine, as 
is direfted in the above procefs. It would not^ 
however, have the un<5luofity of the bcft verdigris, 
which quality is necellary for painting. Good ver<'« 
digris cannot be prepared, except with a vinoaa 
acid, or a folvent partly acid and pardy fpirituous. 
Accordingly the luccefs of the operation depends 
chiefly on the degree of acetous fermentation to 
which the wine has been carried. 

By diftilling verdigris, the acetous acid may be 
feparatcd in a concentrated ftate, and of a ftr^ngth 
equal, or perhaps fuperior, to the muriatic aci(^. 

Copper is capable of a very flight detonation 
with nitre. It decompofes fal ammoniac, and at the 
fame time the volatile alkali is in fome mealiire 
refolved into its conftituent parts, azote and hy« 

Sulphur and phoiphorus may be united to cop* 
per; they deprive it of its metallic fplendor, and 
change it to a black cobur. If plates of copper^are 


laa , Gun and Bell MetaL [Boot Vf» 

ftratifkd in a crucible ivicfi fulphur^ the7 unite, and 
form a compound which is ufed in the dying acd 
painting ef calicoes. Liver of fulphur and hepatic 
gas have a ftrong action on copper; the former 
diiiblves the metal by the dry, as well as by the 
humid way I the latter ftrongly colours the (ur&x^ 
but its tSc6i has not yet been well examined iota 
Oils alfo diffolvc copper, particularly thoie of ao 
fromadc Hind. 

There are few metajs which will not form aUt^ 
with, copper. A metallic, compound is made wki 
arfenic in imitation of filver, but it foon tamiAes. 
In treating of zinc, the procefs for making brafs has 
|]jeen dcfcribed. Pinchbeck is a kind of brafs madfc 
in imitation of gold. Copper is thp bafe of gim 
metal and bell met'd* Gyn metal ^ (kid to ouiM 
of copper, with abeti^ one tenth p$rt of tin j bcfl 
metal, of copper with about one fiftH of tin. It may 
in general be obferved* that a lefs proportion of tin 
is ufed for making church bells than clock bells, and 
that a little zinc is ^ded for the bells of repeating 
watches, and other fmall bpUs. 

Copper, in a ftate of fufion, is liable to a violent 
explofion if touched with any humidity. In the 
cafting of bells and cannon they are particularly 
pareful to have the moulds dry; for if the kaft 
moifture finds accef^, it is fuddenly converted into, 
vapour, and by its expai>fion throws the metal to a 
confiderable diftance, to the great danger of the 
perfons prefcht. 

The beft poffible proportions of copper and tin, 
for^e above purpofes, have never, I believe^ been 

% accurately 

Chapw 30.1 Antiquf Statues md Medals. 1123 

accurattly $fccruincd. The metallic compound 
uied by the Romans for their ftatues and plates for 
infcriptions, is handed down to us by Pliny the na- 
turalift. They firft melted a quantity of copper; 
iato the melted copper they put a . third of its 
■weight of old copper, which had been long in ufcj 
to every hundred pounds weight of this mixture 
they added twelv? pounds and an half of a noixture 
compofed of equal parts of lead and tin. Tin melted 
with copper forms the compound called bronze. 
Of this compound the fpccific gravity is always 
greater than would be deduced by computadon 
from the quantities and fpecific gravities of its com- 
ponent parts. There fecms to be a happy relatbn 
between thele metals, which fits them for forming, 
in conjunction, compounds of great firmneis, den<- 
fity, and clofeneA* Fjom thefe prqperties they 
admit of an excellent polifli, and Pliny accordingly 
informs us^ that the befl; looking glafles of his tinoe 
were made of a compofition of copper and tin. But 
the attention of philofophers. is more particularly 
direfted to the mixture of copper and tin, on ac*» 
count of its being the fubftance of which the ^)e- 
cuiums of reflecting telefcopes are made. Mr« 
Mudge found, after a number of trials, that fourteea 
ounces and an half pf gr^in tin, with two pounds 
of copper, made the beft compofition for this purr 
pofe^ an addition of half ah .ounce more of the Qi^ 
rendered the compofition too hard to b^ prop^erly 

Pot metal is made of copper and lead, the latter 
being one fourth or one fifth of the weight of the 
former. Lead, however, does not fecin to have any 


224 Tmnmg tf Copper. [Book VI 

femarkable attradion for copper^ and docs nocpn* 
mote its fiifion, unleis the lead is heated to a h^ 
degree ; the copper then diflblves with fbme degrecof 
eflFervefcence. On allowing the compound lo coo^ 
the copper feparates agsun^ and forms litde grans b 
the mafs, through which the lead remains difperfei 
It is eafy to feparate the lead again from the copper, 
if the mafs is expoiied in a furnace ; for the bi 
melts firft and leaves the copper; the leadj bof- 
cver, which runs off at firft, contains fbme of ik 
copper, which may be eafily feparated by melo; 
the lead and taking ofF the fcum, which coman 
the copper. Silver is feparated from copper by 
meldng the latter with three times its weight of 
lead; the lead is then melted out, and carries widk 
the filver. The filver is afterwards feparated ftvn 
the lead by the calcination of the latter metal. 

From the bad effefts which have been cxpcrien- 
cedfrom impregnations of copper in aliments drrf- 
fed in copper veffels, it has become a very gencnl 
cuflom to cover thefe vefTcls with an internal ctwr 
of fome other metal. The method of tinning in» 
has been defcribed, and that of rinning copper i 
very fipnilar, except that the compofition for cover- 
ing the furface of copper confii^s of about one pait 
of lead to two of tin, n^hereas iron is covered wiA 
tin alone. Zinc has been recommended as a fub- 
ftitute for tin in thefe operations, and has the ad- 
vantage of fuperior hardnefs. The mediod of tin- 
ning copper veflfels is by making their internal 
furface perfeftly bright, and then wafhing then 
with 9 fplution of fal ammoniac. The: vcffd ^ 

Chap. 30.] Caution in the UJe ef Copper Veffels. aaj 

next heated, and the tin or nnetallic mixture is 
melted and poured into it, and being made to flow 
over every part of the furface of the veffel> it in- 
corporates with the copper, and when cold remains 
united with it. Rofin, or pitch, are fometimes ufed 
to prevent the tin from being calcined, and the cop- 
I)er from being foaled, either of which circutnftan- 
tes would prevent the adhefionof the tin. Bifliop 
Watfon eftimated the quantity of pure tin which is 
ufed in tinning a deBnite furface of copper, and 
found that half an ounce of tin was fpread over 
two hundred and fifty-four fquare inches, or fome- 
what lefs than a grain of tin on each fquare iifch; 
but the fame author fufpefbs, that not a quarter of 
a grain of tin is ipread over a fquare inch in the x 
ordinary mode of tinning, and therefore recom- 
mends it as a neceflary caution againft the coat 
being rubbed off, and the copper beconiing expofed» 
to make it as thick as poflible^ and to ufe tin nearly 

A very excellent method of tinning, and one much 
pradifed in England, is, to make ufe of pure 
tin, and hammer it on the copper. It feems pro- 
bable, however, that when copper velTels are kepc 
y^dl fcourcd, that no danger wiU arife from them in 
the drefling of animal food^ or even of vegetable 
aliments, unlefs fuSered to remain In the ve^ls 
frhcn cold^ 

Vol. 11. a Chap^ 

t 126 1 ^DokYI. 

Chap. XXXI. 


Gre^U JttraAion of this Metal fir the Matttr o/Heat.^^d^ 
rindertdfiUd'y maUtahk^^^Gentral Properties of^ickfiw.^ 
Hydrargyrus calctnatus.^^Naturdl Hiftorj of Mercwryj^m^ 
iar.'^^Native Vermilionj-^ASiou of Adds on this MtteL^t' 
hith Miturai, — Red Precrpitate.'^White Precipitatt.'^mft^ 
Suhlimate.''^a}omeL^KeyfeT^s Pills. — Chiefs MatnL^ 
Vermiliom^AmalgasMs^^^oU made brittle fy Mer€ur/,^Um 
of gilding Metals, — Vfe of^uicifil'ver in extraSing thtfmm 
Metals from the Eartb.*-^Making ofLookikg Glebes, '^Cintnam 
neceffary for the Operation of Mercary on the hkman Boijf. 

THE circumftancc which mdft remafkaHf 
diftinguilhes mercury, or quickfiiytr> fit© 
the other metals, is its ftrong zaaaEHon fbrfao^ 
lb that it retams the ftate of fluidicy at the ordiiBry 
temperature of the atmofphere, and at the tempe- 
rature of 600 degrees of Fahrenheit is amvtitnl 
into vapour; , few of the other metals, therdbi^ 
melt at fo low a point as th^t at which matiiry 
boils and is volatilized. It was bng taken &r gW' 
ed that there was fomething^pccoHar inmetcotyj 
which rendered it neceflarily ftoid; bfut die acade- 
micians of Peterfburg have proved that this is » 
erroneous idea, and fhewn that mercurjr difo 
from other metals merely in the degree of heat at 
which it palTes from its folid to its fluid ftate. Tic 
congelation of mercury has been eSe£ted in a va- 
riety of inftanccs by the help of the nitrous acid an^ 
ftow, or pounded ice, commonly called tbc freez- 

I - 

Chap; 31.3 Mercury in a JiHd State/- . iii 

ing. mixture, and the congelation is found to tafetf 
place at the thirty-ninth degree below o of Fahren- 
heit's thermometeir. Mercury, in its folid fornii is 
found to have confiderable malleabtlity, but this 
fcannot be proved to its foiled extent, becaufe the 
hammering of it produces very foon a d^ree. of 
heat fufficient to melt it. 

Mercury being a metal in a ftate of fufion,' aU 
ways afiefts die form of globules when it is divided 1 
and when it is confined in a bottle, its furface is 
convex^ from the ftrong attraftion of its particles 
for each other. If the veflcl, however*, in which 
mercury is confined, is metallic, its furface appear^ 
concave, from the tendency which ic has to unitfe 
itfelf to the fides of the veflel, which attradion 
tovercomes that between its own particles. 

When mercury is fubmitted to that degree of 
heat at which it is volatilized, and is at the fame 
time expofed t» the aftion of atmofpherical air, 
ic is gradually copverted into a calx of a red co- 
lour, the hydrargyrus calcinatus of the London 
pharmacopeia. A greater heat, however, revives 
this metallic calx^ and at the fame time the vital 
air is again extricated. 

Mercury is not fenfibly afted on by expoAire to 
4ir, but by long continued agitation it becomes 
pardy converted into a very fine black powder. 
The mercury is not changcjd in this experiment, 
iinlefs> perhaps, it fhould be found that it abforbs 
fome part of the vital air contained in the 
vdfcl in which it is confined. By a flight heat, 
Q^a or 

tii Natural H^ofy cf Mercury. {Book TL 

or by trituration in a warm mortar, it may be 
made to refumc its ufual fluidity and brilliancy. 

Mercury is found in the earth, either in its native 
metallic ftatc, or combined with fulphur, when it is 
called cinnabar. Running mercury is found in 
globules, or larger mafles, in friable earths or ftoncs, 
and moft commonly in the clefts or cavities of m 
ores. It is niore frequently, however, imbedded 
in calcareous earths or clays of different colours, 
from which it may be feparated either by tritura- 
tion or lotion, the fmallcr globules coalefcing by 
mutual contaft into larger j or by diftillation. 

More mercury is found in the ftate of Cinnabar 
Aan in its metallic form. This ore confiffcs of 
mercury and fulphur combined together in differ- 
ent proportions. Cinnabar is fometimes found in 
the form of a brilliant red powder, and is then 
called native vermilion, fometimes in an indurated 
ftate, and though generally red, has been fome- 
times obferved of a yellowifh or blackilh calt It 
it is moftly opake, but fome fpecimens arc as tranf- 
parent as a ruby. 

Mercury is too volatile to adnftit of the fulphur 
being feparated from it by roafting ; thefe (ubfbances 
are both fo volatile that they would rife together. 
In order" to feparate mercury from its ore it is ne« 
ceffary to add quick lime, or iron filings, unk& 
fome fubftances of a fimilar nature happen to be 
naturally mixed with it; the mafs is then fub* 
mitted to diftillation, and the calcareous earth, or 
iron filings, by fuperior attraftion, detain the ful- 
phur, while die mercury comes over in the ftate rf 



Chap. 3 1 .] Turhitb Mmeral. a %^ 

vapour, and is condenfed in the Teceivcr. Differ- 
ent cinnabars yield from three parts to (even parts 
in eight of their iveight of mercury. Mercury 
has fometimes been found united with the muriatic 
and vitriolic acids, and with the ores of fomc other 
metals. It is thought to be not abundant in na« 
ture 5 but this opmion may be partly owing to its 
volatility, which may prevent it from being dif- 
covered in many minerals that may contain it^ 
Moft of the mercury in commerce « afforded by 
the mines of Idria in the Auftrian dominions, Al- 
maden in Spain, and Guancavelica in Peru. 

The vitriolic acid docs not aft on mercury un- 
lefi concentrated and conGderably heated j it then 
corrodes it into a white mais, and the vitriolic acid 
is rendered partly volatile by the abftradKon of 
oxygen. The greateft part of this mafs, which 
weighs confiderably more than the mercury made 
ufe of, is a calx of mercury united to a fmall por- 
tion of vitriolic acid, but part of it is a perfcft fait, 
formed by the union of the vitriolic acid and mer^ 
eury. If boiling water is added to it, it affumes a 
bright lemon colour, which is owing to^ the abK 
ftraftion of the vitriolic acid, the prtfcnce of which 
rendered the mafs white. The more boiling water 
is ufed the yellower is the remaining powder, 
which, after repeated effufions of water, is found 
to have no .caufticity, and to be nearly a pure 
calx of mercury. This is the fubftance known 
under the name of turbith mineral. The water, 
which has been poured on tlic vitriolic mercurial 
0^3 'mafs. 

ji^o Mim of Nitrous Aui ot$ lAarcwrj. [Book VI* 

' Tos&j is found to contain a confiderable qu^mtit/ 
of vitriolic acid united to the calx of mercury. 

The nitrous acid is decompofcd by mercury 
with the greateft rapidity. Strong nitrous acid wiU 
jtake up its own weight of mercury in the 
cold, and this folution will bear to be diluted with 
.water. .If the folution is made by the affiftance of 
heat, a miich larger quantity is diflblvedi but a 
precipitate is produced by the addition of water. 
If cold water is employed, a white precipitate is 
afforded, but if hot water the precipitate is of a yel- 
low colour, and greatly refecnbles the turbith mineral 
produced by the vitriolic acid. If acid is added 
to the folution p^pdpced by heat, it is not decom<» 
.pofed by water. This folution is very ponderous 
,z,tA acrid, and ftains the ikin of a deep purple, in- 
clining in appearance to black, a portion of the 
mercury being precipitated by the animal rqatter, 
. while the acidafts on it, Cauftic alkali, added to this 
folution, precipitates a pure calx^ mild alkali, a calx 
combined with carbonic acid. The volatile alkali 
precipitates the mercury in the form of a dark grqr 
jx)wder. When this precipitate is examined, it 
is found to contain a quantity of mercury in its me- 
tallic ftate. If this matter is dried and rubbed oi^ 
pure goid, it turns white, by which we may difcovcr 
fmail quandries of mercury in the metallic ftatc. 
^he near approach to the metallic ftate, obferved in 
the precipitate afforded by the volatile alkali, feems 
to be owbg to the prefence of hydrogen, which is 
one of the. conftituent principles of volatile alkali| 
'^d which has a ftrong attraiStionfor oxygen, 

^ • ' ^ ' The 

Chap. 3 1 .] Rjsd Prepipme^ &?r. 23 1 

The precipitates of mercury; formed by alkaline 
intermediums, have a property difcovered by M. 
Bayen, which muft not be paffed over in filencc. 
They detpijate like gun-povdc^r, when cxpofed in 
cm iron fpopn to a gradual heat, after haviiig been 
triturated in the quantity of half a drachm, with fix 
grains of flowers of fulphur: after the detonation, 
a yiolet pos^der r<?mains, which may be fublimcd 
into cinnabar. 

The nitrous ^cid may be fepar^t§d from mercury 
by heat alone. le firft effect is to evaporate the 
^ateiy parts $ ^er this the acid Sies off* in deep 
coloured fumes j as the acid evaporates the c^x be* 
comes yellow, then of a deep red, but when re- 
moved fomc time, orangp. This is the red preci- 
pitate of the fhc^ The nitrous acid, therefore, 
as iQ the cafe of other metals, though it ads 
with more rapidity, adheres with lels force to the 
mercury than the vitriolic acid, which adjts (lowly 
and with difficulty. This proceeds, as was before 
mentioned, from the eafe with which the nitrous 
acid is decpmpofed, fo as to afford to metals the 
oxygen which is neceffary to render them ioluble. 

The muriatic acid has no a&ion on mercury in 
its metallic ftate, becaufe it cannot part with the 
oxygen necei&ry to calcine the metal. It has, not- 
withftanding, a very ftrong attraction for mercury, 
and diflblves it with great readinieis when the latter 
is previoufly reduced to the ftace of a calx. If a 
fmall quantity of muriatic acid is poured on a 
nitrous folution of mercury, it feizes the metal, and 
fonns a fait, which is precipitated in the form of a 

Q^Ac whitifh 

ija Corroftve SuhJimate. tBoAYL 

whitiih coagulum^ which^ whendricd^ is called wtis 
precipitate, and is a kind of corrofivc fublioiste. 
The marine falts, with baft of alkali, or of aw 
faline terreflrial fubftance, iuch as lime, magncfii, 
&c. produce the fame cffc6t, except that ia 
this cafe, though the precipitate is the fame, tk 
nitrous acid, inftead of being left uncombiaed, 
unites with the bafis of the marine fait which was 

If mercury, corroded by the vitriolic or nirrow 
acids, and dried, is mixed with powdered fca fek, 
and expofed to heat, a double attraction takes pkcc; 
the nitrous or vitriolic acid deferts the metal to 
unite with the fixed alkali of the commoa i^ 
while the muriatic acid feizes upon the mercury, 
and forms a metallic fait, which, in the degree of 
heat ne ceflary for the operation, proves volatile, and, 
rifing in vapour, is condenfed in a fblid form ifl the 
upper and cool part of the veflcl employed. TAis 
is the hydrargyrus muriatus, or corrofivc fublimatt, 
which is a very acrid and powerful preparation of 

The mild preparation, called calomel, is obtained 
by rubbing three parts of mercury, in its metallic 
ftate, with four of corrofivc fublimatc, till thcf 
form a greyilh powder ; the mafs is then fublfm- 
cd*, and forms a fubftance like corrofivc fublimiic, 
but more ponderous, and of a more filvery appear- 
ance. The ingredients, however, are not fufficicntly 

* Made volatile, or raifed in vapour, by the applicau^^^ 


Chap. 31*3 Calomely 6?^. 233 

mixed by the firft fublimadon ; they muft be rub* 
bed together again and ful^limed ^ and thefe {^ro* 
cefles muft be repeated at leaft three times. 

The converfion of the corrofive fublimate into 
the milder fubftance, calomel, may be explained on 
the following principles :— In the corrofive fubli- 
mate, the muriauc acid is found to be combined 
with a very large quantity of oxygen, which renders 
it extremely aAive. By the addirion of mercury, 
a quantity of this fuperfluous oxygen is abftrafted, 
for the calcination of the additional metal; and the 
whole mafs, therefore, contains the acid not only 
in a milder ftate, but the fame quantity of acid is 
difibfed through a larger mafs of the metal. 

Ponderous earth, magnefia, and lime, decompofe 
the corrofive fublimate, and precipitate a mercurial 
calx. The phagedenic water, nnade ufe of as a cor- 
rofive by furgeons, is made by throwing half a 
drachm of corrofive fublimate, in powder, into a 
pound of lime water 5 a yellow precipitate is then 
formed, which renders the liquor turbid. 

Acids and neutral alkaline falts produce no 
change on corrofive fublimate, but it contrads an 
intimate union with fal ammoniac without decompo- 
fition. The fal ammoniac renders corrofive fubli- 
mate very foluble. The calx hydrargyri alba of the 
London Pharmacopeia is obtained from this com- 
bination. A quantity of fal ammoniac is diflblved in 
diftillcd water i an equal weight of corrofive fiib- 
limatc is then added -, when this is diflblved, fixed 
vegetable alkali is added, which produces a white 
precipitate. In this operation the fixed alkali dif- 


^34 W<^'^ P^^^ Eibiofs Mineral, &fr. £Book VI 

^ng^ges the volatile alkali of the fal ainmooiacjwiui 
precipitates the mercuiy in the fonn of a idii 
cab^» This preparation is chiefly ufed in Uaimao 
externally. It is fometimes adulterated wkhce- 
ruicj as the red precipitate is with minium. Tk 
friud may be difcpvered by expofing a linail qoo- 
tity to heat in a fpoon ; if pure they will be o- 
tirely difli'pated, but if they contain lead, or ode 
impurities, thefe matters will remaiivbehiod. 

If the f^lt formed by the conU:>ination of i(^ 
toui^ acid with the fixed vegetable alkali, cob- 
monly calledregenerated cartar, or kali acetatuio,s 
added to the folution pf quickfilver in the mooa 
acid, a double exchange takes place ; the sM 
unites with the nitrous acid, while the acetous acid 
enters into combination with the mercuiy, «aiis 
precipitated. This precipitate (being purified If 
foludon in hot diftilled water and filtrstioojbs 
nearly 'the lame medical properties as cdomel, vi 
is fakl to form the bafis of Kcyfer's pills. Tkf 
acetous acid does not aft on mercury unlcfi wte 
reduced to the Hate of a calx. 

As mercury is commonly, in a ftatc of nawK> 
combined with fulphur, fo it may be artificial 
united to it with great e^fe. When one partof tte 
metallic fluid is triturated with three parts of flo»«3 
of fulphur, the mercury gradually lofcs its metallic 
appearance, and is converted, by its union wicbBic 
fulphuri into a black powder, csdled Ethiop'sfflJ* 
neral. This combination is more quickly cffc*° 
by mixing the mercury with melted fdjAur. ^^ 
this compound is expofcd to a confidcrablc <3^ 

pf heat it takes fire, the greater part of the fulphur 

burns^ and after the combuftion a matter remains, 

which, when pulverised, is of a violet colour. To 

convert this powder into cinnabar it is put into ma- 

^trades *, which are heated till their bohoms be- 

4conric red, and kept in this ftate for feveral hours, 

till it appears that the matter is entirely fublimed. 

The Dutch prepare, in the large way, the cinnabar' 

employed in the arts. When much divided by levi- 

Ration f it has a brilliant red colour, and is called 


Mercury has the property of uniting itfelf to many 
pfthe metals^ by penetrating their fubflance, and- 
jrendering thenn more or lefs foft, according to the 
proportion of mercury employed. If the pro- 
portion of quickfilver is very great, the mixture i^ 
like quickfilver, and is only diftinguilhed from if 
by an appearance of foulnels. If a fmaller quantity 
48 ufed, the mafs is foft like butter; if ftill lefs, it is 
folid but brittle. Thefe mixtures are called amal- 
gams. It readily combines in this way with gold, 
filver, lead, tin, bifinuth, and zinc, but not eafily 
with arfenic and copper, and fcarcely at all widi 
iron, pladna, nickel, or cobalt. Its a£tion on the « 
other metallic bodies has not been afcertained. 

A piece of gold, being rubbed with (Juickfilver, 
is foon penetrated by it, and is rendered fo fragile 

* Yeflels tt(ed in chemical operations^ of glafs or earthen* 
ware, generally of the ihape of an egg, and open at the top, 
(he necks are long or Ihort, as occaiion may reqidre* 

j- Reduced to a £ne powder. 


^2^ Gilding in Or Moulu. [[Book Vl 

that It may be cafily broken. A gold ring, wKd 
has become fo tight on the finger that it cannoc be 
drawn ofF, may be eafily removed in this manca 
Gold, united with quickfilver in certain proponioc^ 
forms a ki.Md of pafte. On this property is founded 
the pruccfs of gilding in or moulti. A Imall quan- 
tity of this parte is Ipread upon the furfacc of & 
copper which is to be gilded in or mouluy and ^ 
metal is then expofed to heat. Quickfilver evapo- 
rates in a far lefs degree of heat than is fxi&am. 
to melt cither gold or copper i when, therefbrc^ik 
mixture of gold and quickfilver Is expofed to hrt, 
the quickfilver is driven off in vapour ; but tfcc 
gold, not being fufceptible of evaporation, rem£« 
attached to the furfacc of the copper, and unde^ 
ing the operations of burnlfliing, &c. the latter i$ 
gilded, or gilt. This method of gilding copper, bf 
means of gold and quickfilver, was known to rfe 
Romans. The furfacc of iron cannot be covered 
in the fame way with goldi but the iron, by 
being moiftened with a folution of blue vitriol, a 
in the proccfs for browning firelocks, and being tbia 
covered with a lamina of copper, becomes as fuf- 
ceptible of being gilded as if its whole lubflaoa 
was copper. 

It is this property which quickfilver has of unit- 
ing with the precious metals, and diflblving thenij 
which has rendered it fo ferviceable in the cxtraaioo 
ci them from the earth with which they arc mbced 
The earth or ftones, in which gold and filver arc 
contained, being reduced to powder, are mixed widi 
quickfilver, which diflblvcs. every particle of the 


G^ap. J I.] Amalgam of Tin axid Meriury* ^yj 

pcecious metals without contrading the lead union 
with the other matters ; the quickfilvcr is then 
clriven off by heat, and, being condenfed in the re- 
ceiver, is again employed in the fame procefs. The 
gold and filver are feparated from each other by 
proccffes, which will be defcribed in treating of 
thofe metals. Since the difcovery of the American 
gold mines, the confumption of quickfilvcr has 
been much increafcd. Hoffinan conckides, from 
calculation, that fifty times as much gold as quick- 
filvcr is annually extrafted from the bowels of the 

Looking glaffes are covered on one fide with an 
amalgam of tin and mercury. Tin, being beaten ' 
into thin leaves, is called tin foil ; on tin foil, evenly 
dtfpofed on a flat ftone, quickfilver is poured, and 
fpread with a feather until its union has brightened 
every part of it ; a plate of gkifs is then cautioufly 
Hfd upon the tin foil, in fuch a manner as to fweep 
off the redundant quickfilver which is not united 
to the dn ; weights are then placed on the glafs fo 
as to prefs out ftill more of the quickfiUer, and in a 
litdc time the tin foil, thus united to the quickfilver, 
adheres fo firmly to rhf glafi that the weights may 
be removed without any danger of its falling off. 
About two ounces of quickfilver are ufed in cover- 
ing three fquare feet of glafs. 

In order to make mercury capable of afting on 
the animal body, it is nece0ary that it (hould under^* 
go feme preparation i for its particles muft be very 
minutely divided before they can enter the veflels. 
T|ius, if wc apply quickfilvcr to a capillar)' tube, 


Ac attraftion of its pardcles fer each other is ft 
ftrong that they will not rile In it ; but minuted 
tifion is ndt the only drcumfhince neceflarytoiB 
^£tivity, for Ethiop^s mineral and cinnabar taka 
into the body have very little if any efieft. Oip 
genation feems to be the moft eflendal circuoifhacQ 
for in whatever way this is ctfeftcd the mercu^ h> 
comes very active *. 

Mercury, in pafling through the body, is rcduol 
to the metallic ftate, and, exuding dirougK the poRV 
fomctimes attaches itfelf to the gold of wad«i 
rings, flceve-buttons, or car-rings, and roAn 
them white. 

* Does not the effed of fulphar, in diminifhiag AeaMf 
of mercurul prq>ar2^tions» depend on it9- fapeiiof ttto&t^ 
for oxygen> by which it has a tendency to redact the weoff 
to the metallic ilate? 


Chap. 32.] [439 1 


Chap. XXXIL 

SILVER. * , 

Charaatr of the pirfi^ Metals.'^General Prof erf its of Siherj^ 
Vegetation of Silver. ^^Natural Hiftory of Silver. -^Jfa^ing of 
8il*ver. — Cupellation.'^Lunar Cauftic.^Fulmtnating Siher,^^ 
Luna Cornea.-^DiawCs Tree.^^Green Gbld. — Standard Silver 
Coin.-^Plating ntnth Siher; honv ferformed.^Frhtch Plate. 

OF the different metallic fubftances only three 
have been dignified by chemiftsand mineralo- 
gifts with the appellation of perfeft, viz. filrer, gold, ! 
and platina. Thefc are difti^guiflied from the other 
metals by their weak attra6H6n for oxygen, wMch 
enables them to retain their purity and metallic 
fplendor in fituations in which other metals be- 
come gradually covered with ruft or cabc. Silver 
is the whiteft of all metals, and is poffeffed of great 
brilliancy J it is harder than gold; in weight it is 
exceeded by gold, platina, quickfilver, and lead; its 
gravity being only about ten times that of water. Its 
malleability is fo great, diat a grain of it reduced to 
ofdinaty filver leaf meafures about fifty-one Iquare 
' inches, in which ftate it is not more thati the hundred 
and fixty thoufandth* part of an inch thick, which, 
however, is coAfiderably mq;c than one tMrd thick* 
er than gold leaf. Its tenacity is fo confidcraH^ 
that it niay be drawn into wire about half die thick- 
hi& bf a fine huhian hair, and a wire of one tenth of 
arfinch in diameter wffl fupport the Wright of two 



240 Vegeiatbm of Siher. [BookVL 

hundred and feventy pounds without breaking. It 
is very fonorous, but in hardnefs and elafticityiti 
not equal to copper. It hardens under the hammcTi 
but very readily lofes that hardnefs by heating. 

Silver, expofed to the heat of the moft powoM 
burning lenfcs, is pardy vitrified and panly vofad- 
lizcd in fumes, which are fbondj whai received (a a 
plate of gold, to be filver in the metallic ftatc. Itb 
like wife faid to have been partly calcined by nwJf 
fucceffive cxpofures to the heat of the porcdi 
furnace at Seves. This, however, may bedoubtttj 
as filver docs not undergo any degree of calcinaooi 
by expofure to heat, even with the addition of flint 
Silver melts in the firft degree of white heat, aid 
appears in the fire like the fineft quickfilvcr. Wha 
it is hafl:ily cooled, it exhibits a curious phcnonw- 
non, calkd vegetation; for we difcover from diffe- 
rent parts of its furface ramifications and brancw 
like thofe of trees which fprout out with a to 
The rcafon of this appearance feems to be thcint- 
giilar contraftion which the filver undergoes fl 
pafling from the fluid to die folid fliate. Thcmcltci 
filver fufFers the firfl: commencement of congetoon 
at its furface; by thefe means a cruftisfonnW) 
which by its fudden contradion comprclTcs tnc 
fluid filver within; thus a protuberance is iorm 
which, congealing in its turn, contracts and ^td^ 
the intermediate fluid through its cruft ^ 

The air alters filver very little, unlels it coocais 
fulphureous vapours, which it oftien docs, fromth^ 
jUitr«fadtion of animal fubftanccs or the cxhalaooos 

Chap. 3d;] Narard t^ftory- of Silver. a+x^ 

of drainS) or of fulphureous mineral waters. This . 
metal, therefore, .becomes fomcwhat tarniflied by 
long continued expofure to the atmofpherc, and in 
time becomes covered with a thin purple or black, 
coating, which, after a long fcrics of years, has been./ 
obfcrved to fcale off from images ' of filver expoied 
in churches, and was found, on examination, to , 
confift of Giver united to fulphur. 

Silver is often found in its native date, and may 
be known byr its brilliancy and duflility. It is . 
fometimes met with in irregular mafies, fometiniei 
it the form of capillary threads or fibres, and fbme-> 
times in that of branches, formed by oAahedrons 
inferted one into the other* It is alfo often 
dilperfed in a quartzofe gangue.* Narive filver is 
fometimes found alloyed with gold, copper, iron, . 
or regulus of antimony; but hative gold much 
oftcner contains filver than native filver does gold. 
Silver is not naturally found in the ftate of calx. 

The vitreous ore of filver is compofed of that 
metal and fulphur. It is the richeft of the filver 
ores, and yields from feventy to eighty pounds of 
the metal in the hundred weight. It is of a black- 
ifli grey colour, refembling lead \ fome fpecimens 
are brown, greeniih, yellow, &c* \ it may be cut with 
a knife, and is fometimes cryftallized. If it is ex- 
pbfcd to a heat not fufficient to melc ic, the fulphur is 
diflipated, and the virgin fijver is obtained in fibres^ 

* A quartzoie or fparry eryftallkation, often found inclolinj; 
the ores of metals^ and therefore called the matrix or rider^ 

Vot.IL R The 

Ht Natural tSft&ry efS^oer. [Book VL 

The red filvcr ore contains arfenic as well as fcl- 
phur. It is a heavy ftiitiing fubftancc, fomctimK 
tranfparcnt, fbmetimes opake, but commonly cnf- 
'tallized. It is often of a deep red colour on the out- 
flde, but appears paler within. It affords about 
half its weight of filver. If it is cxpofcd to a ftt 
carefully managed, and capable of ignidng it, the 
filver is reduced, and forms capillary fibres, finnhr 
to native filver. 

There is a filvcr ore containing arfenic, cobalfi 
and iron, mineralized by fulphur. This ore fotnc- 
times yields half its weight of filver; it varies in is 
appearance, being fometimcs of a grey and brillia* 
aipcift, but often of a dull and tamifiied colour, wii 
cfflorefcenccs of cobalt. The goolf dung ore b^ 
longs to this Ipecics* The grey ore of filvcr con- 
tains a large quantity of copper. The black ffl^ff 
OT^y called nigriUo by the Spaniards, feems tobea 
middle ftate between native filver and fomc of fc 
ores, or thofe ores in a ftate of impcrfcft dccoonpo- 
fition. The corneous filver ore is a natural combi- 
nation of filver and muriatic acid with a fetfH 
quantity of vitriolic acid. Silver is alfo found » 
confiderable quantity in the ores of other n^ 
particularly thofe of antimony, zinc, lead, w» 

In the aflaying of filver ores different proafc 
are ufed, according to their nature. When fcuw 
in its metallic ftate, nothing more is neceffiry tbafl 
to fcparate it from the earthy or ftony maltcria 
which it is embedded. With this view it « ^ 
cxpofcd to heat, to render the ftony matter friabfc 

Chap. 32-1 Ctipelktion of Siher. 543 

The mafs is then mixed and ground with quick- 
filver. Thus the filver is converted into an amal* 
gam> which, from the intimate union of the particles 
of the metals, is fpecifically heavier than quickfilver 
itfclf. The ftony matters are now eaGly waflied oft 
without lofing any of the metal. The quickfilver 
is afterwards partly Separated by fqueezing it 
through a piece of leather, and the remainder by 
diftillation. Sulphureous filver ores require to be 
firft roafted, and then mixed with a quanti^ of 
fiux. . In order to feparate lead, copper, iron, &c» 
from filver, a particular procefs is empbyed, which 
iscalkdcupellation, from the veflel in which it is per- 
formed, called a cupel, and which is chiefly formed 
of calcined bones, and is very porous. The metal- 
iic. mafs containing filver is mixed with a confider- 
able quantity of lead, and then expofed on the 
cupel in a ftate of fufion« . The lead is vitrified and 
abforbed into the cupel, carrying with it the imper- 
fect metals, and the filver remains behind on the 
cupel in a pure ftate« 

The vitriolic acid a<^ on filver as on the other 
metals, with the afiiftance of heat; it then cor- 
xodes it into a white mafs, which is ibluble In 
water, and by evaporation affords fmall cryftals. 

The nitrous acid diflblves filver with great rapi- 
dity. When the ftrong nitrous acid is diluted with 
an equal weight of water, it is capable of diflblving 
about half its weight of filvec If the filver em- 
ployed is quite pure, the fohi&on is limpid like 
water; but as filver commonly contwis a litde 
copper, its. folyti^ have ufually a Uueifh tiage. 

Ra - If 

*44 M(?itf of iymg the Hair brown. [Book VI. 

If the filver employed contains gold, in this cafe, 
' as the nitrous acid is not capable of difTolving tbt 
gold, ic feparates from the filver in the form of 
blackidi flocks. From this difference in the a^oi 
of nitrous acid on filver and gold, it is fuccefsl'oB/ 
ufcd to feparate thcfe metals from each other. 

The folution of filver in the nitrous acid is a- 

tremely bitter and^cauftic, and has the property of 

changing the (kin or hair to a black colour, or, if 

very much diluted, to a brown, and formerly, when 

. the caprice of iafhion abhorred light hair as tnudi 

as it at prefent admires it, was employed for An 

purpofe. The colour is, however, very faint when 

the folution is firft applied, and the produftionof 

colour fcems in a great meaiure to depend on Ac 

adion of light. Dr. Lewis mentions a remaikaft 

phenomenon, which this folution prefcnts when 

added to chalk or any pure abforbent earth. Tk 

chalk and folution are both at firft quite white, ao* 

will continue fo if kept in a dark place, but if «• 

pofcd to the light they foon become black; (o thatif 

a quantity of this mixture is put into a glafs ^ 

icaicd up, any marks or letters may be made B) 

appear on it as if by magic. To cffc6t this, & 

phial is covered with thick paper, in whidi the 

marks or letters are nicely cut, and it is then ex- 

pofed to the light, which, adting only through tkc 

.apertures of the paper, produces the efFcft. ^^ 

the ftains are produced, aqua fortis, by rc-dJffolw? 

the filver, will niakc them difappcar again, k 

therefore feems, that the produdion of cd^'^ 

•wing to an impcrfcdk reduction of the filver, ^ 

♦ tin: 

Chap. 31.] "" Lunar Cauftic. 245 

that the a<9;ion of lijght difengages oxygen from 
this compound in the fame manner as it docs from 
the pale nitrous acid, and from vegetables. 

When this folutlon of (ilver is evaporated with a 
gentle heat, it may be made to afford cryftals nearly 
refembling thofe of nitre. Thefe, being meked 
in a crucible, are freed from water, ani being 
poured into moulds of a convenient form, become 
the filver or lunar* cauftic, or argentum nicratum 
of the pharmacopoeia. 

Silver is never given internally, and this is the 
only preparation of it made ufe of externally. The 
nitrous acid may be entirely feparated from this 
compound by heat alone. 

Silver, however, is moft conveniently feparated 
.from its nitrous folution by immerfing pUtes of 
copper in it. The copper is then diffolved, while 
t*.c (ilver is dcpofited in its metallic ftate. This 
metal may be ftparated from gold by exppfing the 
mixed metals to the aftion of nitrous acid, which 
diflblves the filver and leaves the gold, and the 
above method is ufcd to obtain the filver fix)m the 

To make the famous fulminating filver, which is 
fo truly formidable in its efFefts, a fmall quantity of 
filver is diflToIved in pale nitrous acid (or aqua fortis) 
from which it is precipitated by lime water. The 

* A name taken from the whim of the alchemidi , who called 
.the metals by the names of the heavenly bodies: gold* Sol; 
filver, Luna; copper, Venas; iron. Mars (whence martial 
vitriol, &c.); lead, Saturn; tin, Jupiter; ^uickClver, Mer- 
cury, &C, V . 

R 3 calx 

a46 Fulminating Siher. [Book VI. 

calx or prccipitatt is to be dried by cxpofure m ifie 
^r for three days. The inventor, M. Bcrtholc^ fiq>- 
pofes the aftion of light to have alfo fomc inBuence 
in the fuccefc of the experiment*. The dried calx 
is then agiuted in a folution of the cauftic volacSc 
alkali, when it affumcs die form of a black powder, 
which is left to dry in the open air. The fuiminadng 
filver then confifts of an union of the calx of fihrcr 
with volatile alkali. 

The efFefts of this preparation arc tremendoosi 
and infinitely exceed thofe of gunpowder, fulmi- 
nating powder, or fulminating gold. It expkxies 
with the {lighted agitation or friftion. The ^Uii^ 
of a few atoms of it from a moderate height pro- 
duces a violent detonation, and a drop of water 
falling upon it has the fame efFedt. When it s 
once fully prepared, it muft not be touched or 
snoved into any other veffel, but muft remain i& 
that in which it was dried j and to make the expe- 
riment with tolerable fafcty, not more than a graia 
of filver fhould be employed in the procefe. The 
caufe of thefe explofions has been already infr 
mated in the chapter on ignition, and will be further 
illuftrated in treating of fiilminating gold. 

Though the nitrous acki diflblvcs filver wii 
greater eafe, it has not fo ftrong an attradion fcr 
it as the muriatic or vitriolic acids. Either of thefe, 
dropped into the nitrous folution, feize the filver, 
and forming a compound not equally folublc pro- 
duce' a precipitation. The neutral lahs, containiiig 

• Journal dc Phyfiqoe for Jane 1768, pr 474. 


Chap. 3a»] MiontfMariatU Acid on Silver. 247 

vitriolic or muriatic acid^ have the fame effcdb. 
This difFerencc of affinity between the acids and 
filver is the foundation of a procefs for obtaining 
the nitrous acid in a date of great purity. The 
iblution of filver in nitrous acid is poured into the 
impure nitrous acid till no more precipitate is 
formed. The jnuriatic or vitriolic acids contained 
in the mixture are thus carried to the bottom by 
their union with the filver. The acid \% then de- 
canted and diftilled to free it from the fmall quantity 
of fait of filver which it may ftill contain. 

Notwithftanding the muriatic acid has the ftrong-- 
eft affinity with filver of all the acids, it is never- 
thclefs incapable of diffolving it unlefs the metal is 
in a calcined ftate, or itfelf fuperoxygenated* The 
common method of effeifting this union is to add to 
the folution of filver, in the nitrous acid, any faline 
fubftance which contains the muriatic acid; it is no 
matter to what the acid is joined, whether alkali, 
earth, or metal ; it immediately fcizes the filver, 
and leaves the other matter to unite with the nitrojjs 
acid. Common fait is generally ufed, and the wh^e 
precipitate, which is immediately formed, has the 
appearance of a coagulum. The compound thys 
m^de is fo infoluble in water, that there cannot be 
a nicer teft of the prefencc of the muriatic acid, gr 
common fait, in waters, than the nitrous folution of 
filver i for if the moft minute quantity of either arc 
prcfcht a precipitation is produced. 

This compound has many other qualities befidea 
inibJubility in water. If we coiled it, and wafli off 
th^ falifie matter^ it appears as a fine powdef^ and^ 

R4 whcii 

24^ Luna Cornea. [Boc^E 

vrhen heated to a fuf&cient degree, melts ktot 
fubftance of (bme tranfparency. From its tranfpa- 

'.rency, flexibility, and foftnefs, it is called Im of- 
nea^ or argentum corneumj and from this fe?enl 
other compounds of metals with the muriadc add 
have been called cornea. It may be cut intotnui^ 
parent veflels rcfembling glafe. 

Aqua regia, or the compound of nitrous «d 
muriatic acids, a£b ftrongly on filver, but forms 2 
precipitation in proportion as it (eparates it from 
the mafs. This effc6l may be readily undciilood 
from what has already been obferved. The ni- 
trous acid diflblves the filver, and the muriadc fcize 
it, and forms luna corne/iy which is infoluble. Tiii 
procefs may be ufed to feparate gold from filver; 
the gold is held diflblved in the aqua regia, but k 
filver is precipitated. 

After filver has been reduced to the cakifcnn 
ftate by folution in nitrous acid, and precipitation bf 
alkalies, it is capa^ple of folution in vinegar, anil 
even in lemon juice ; but thcfe compounds havcnoi 
been applied to any ufe. 

To have filver perfcftly pure wc muft ufe quick- 
filver, which, if poured into a folution of filver, a 
attraftcd by the acid, and precipitates an amalgam 
with the filver at the bottom of the vcffcL Tte 
quickfUver is eafily feparated from the filver by 
heat alone. A curious phenomenon arifes f^ 
this amalgam J Jl kind of cryftallization takes pbcfj 
which is formed by the union of the filver i^ith the 

' running mercury. The amalgam puts forth ftooft 

Chap. 34.] Diana* s Tre^. ^49 

^hich afterwards put forth others, like the branches 
of a tree. The cryftallization varies according to 
^the conduft of the procefs> and does not alwajrs 
anfwer, particularly if the mixture is fhaken. It is 
called arhr Dian^y or Diana's tree *. The method 
of making it moft beautiful is very tedious^ and 
would require the fpace of a month. 

This phenomenon feems to admit of explanation 
prccifcly on the fame principle as the branching 
of pure filver when pafling from its fluid to its 
■ folid fVate. The amalgam of filver and mercury 
* is fpccifically heavier than either of the metals in a 
icparate flate, and their union muft cohleijuently be 
attended with contradion. The filver, therefore, 
being precipitated on the furface of the mercury^ 
in proportion as the latter metal is diOblved by its 
fupcrior attraftion for the acid, the mercury be*' 
comes furrounded with a crufl, the contraftion of 
which forces out its fluid contents ; the excrefcences 
thus produced being in their turn covered with a 
cruft of amalgam, are again compreflW, and pro* 
duce fmaller protuberances, and if the experiment 
is properly condufted, the brittle amalgam of the 
metals aflbmes a cryftallized appearance, and the 
form of a thick bulh. In this experiment it is nc- 
ceflary that there fhodld be not only as much mer- 
cury as is fufficient "to precipitate the filver, but 
befides this a quantity remaining in its fluid ftate, 

• Diana's tree, from the whim of the alchemifts alre^y ts(w 
ticedy who appropriated Jilver to the Moon or Diana, aa ftated 
in a preceding note. 


&50 GrmGold. [Book VI 

tx> unice with the precipitated filver into an vsit 

Sulphur has a remarkably (Irong affinity lidi 
filver, and forms with it a compound which bsD: 
appearance and foftncfs of lead. "This metal feon 
alfo capable of attrafting fulphur from antiawny. 
But though filver has fo ftrong an attradion k 
fulphurj gold has none^ and this furniihes a mcthoi 
of ftrparating thele metals by fiifion. 

With gold, filver forms a pale alloy, thcgrto 
gold of the jewellers and gold beaters. This mii- 
ture, however, is not made without fome difEcukf, 
on account of the different ipecific graviucs of tie 
two metals. It does not unite well with pkia 
It forms an alloy with iron, but the properties of it 
have not been well examined into. With hi i 
forms an ajloy^ which is much more fufiblc tiaa 
pure filver, and feems in all rcfpcds to be of » 
intermediate nature between thefe metals. Coj^ 
increafes the hardnefs of filver, and renders it mat 
fonorous, *vithout impairing its ducftUity ox ooJoar» 
when the copper does not exceed the twelfth prt 
of the weight of filver employed. The (laDdarJ e 
filver coin is eleven ounces two pennyweights, troji 
of filver, and eighteen pennyweights of copper. 

The purity of filver cannot be accurately afer* 
tained without fubmitting it to cupellation will 
lead, and its purity is calculated according to <^ 
weight it ^ofes in that procefs. Silver is diviik* 
into twelve imaginary parts, called pennywcigfc^'. 
If it only tofes one twelfth part of its weighs lifl 
cupellation, it contains eleven twelfths of pui«^ 

Chap. 3a.} Platfftg. 251 

ver, and is faid to be eleven perihy weights fine; if 
it lofes two twelfths, it is ten pennyweights fine, 
and fo of other proportions. For greater accuracy, 
each pennyweight is fuppofed to be divided into 
tv^enty four grains. 

The covering of the furface of copper with filver> 
or plating, is performed in the following manner: 
* Upon fmall ingots of copper, plates of filver are 
bound with iron wire, generally allowing one ounce 
of filver to twelve ounces of copper. The furface 
of the plate of filver is not quite fo large as that of 
the copper ingot. Upon the edges of the copper, 
which are not covered by the filver, a little borax 
is put, and by expofing the whole to a ftrong heat, 
the borax melts, and in melting contributes to melt 
that part of the filver to which it is contiguous, and 
to attach it in that melted ftate to the copper. The 
ingot, with its filver plate, is then rolled under fl:cel 
rollers, moved by a water wheel, till it is of a cer- 
tain thicknefs; it is afterwards rolled by hand rol* 
lers to a greater or lefs extent, according to the ufe 
for which it is intended; the thinned is applied to 
the lining of^rinking horns. An ounce of filver ^ 
is often rolled out into a furface of about three 
fquare-fiset, and its thicknefs is about the three 
thoufandth part of an inch; and hence we need 
not wonder at the filver beilig foon worn oflF front 
the fliarp angles of plated copper, when it is rolled 
to fo great an extent. 

* What is commonly called French plate is not 
to be confounded with the plated copper. In 


15a French PUie. -X'^^^kVL 

making French plate, copper, or, more commonh; 
brafs, is heated to a certain degree, and filvcr )ai 
is applied upon the heated meta)^ to which k ad- 
heres, by being rubbed with a proper bir- 

• WatToB's Chemical E&ys. | 


Chap. 53] [ 253 3 

Chap. XXXIII. 


G^fteral Properties of GoU^^-^oU calcined by Eh3ricity,.^^Extremi 
Duadity cf this Metal, — Natural Hiftory of Gold. — Procefis 
far feparaiiug Cold from other ^ubftances.-^^artatunnjm^ 
9' hi ToufhftonC'^^Aqua Regia.^^Rtafnu njohy the different Acidi 
M^ fin metallic Bodies. ^-^Fulminating Gold.'^^Purple PewAr 
of Ca/pus, '^Golden Calf ho-w defiroyed hy Mofes^'^^Uvio^ rf 
Cold luith Qthir Metals ^-^Standard Gold Coin of difftritit 

GOLD is the hcaviefl: of all the metals except 
platinay being between nineteen and twenty 
times rfie weight of water. When pcrfedly pure it 
is almoft as foft as lead, and is neither elaftic nor 
p. fonoroiK. For its fufion it requires rather more 
heat than filver, and when in fufion has a blueilh 
green colour, and its furface is always perfeftly 
bright. The moft intenfe heat cannot calcine i^ 
and only contributes to render it more pure if it 
had any foulnefs. The powerful burning mirrors 
are faid to have volatilized it, and it has been 
driven up in fumes, in the metallic ftate, by flame 
urged upon it by a ftream of vital air. The elec- 
tric fluid, however, when made to pafs in confider-^ 
able quantities through gold leaf, inclofed between 
two plates of gjaft, converts it into a calx, which 
tinges the glafs of a purple colour. 


^54 Katural ISfiufy tfGdd. (Bcx^kTL 

The tenacity of gold is fo great, that a wire ooc- 
tenth of an inch in diameter is capable of fupportkg 
five hundred pounds. Its malleability and du€tilitf 
exceed thofe of filver> and are fo rcmark2d)le, thr 
tlieir limits could never be afcerrained with any ccn- 
fiderablc exaflnefs. On gold lace the thicknefs of tbc 
gold, has been computed to be kls than the <mic h*E- 
dred and thirty-four thoufandth part of an inch,2cd 
tte degree of extenfibility has been carried ftUl fer- 
ther. In ordinary gold-leaf, which is nnade by ham- 
mering plates of gold between fkins,*or animal mem- 
branes, a grain is made vto cover Bfcy-fix fquare in- 
ches and a quarter* In thisftateitsfurface is fbgrca: 
that it may be madeto float in the air with the (lightti 
agitationi and its thickneis is nottnore than the t«o 
hundred and eighty-two thoufandth part of an edcIl 

Gold is produced by nature very plcntifuUy- 
There is much of it in Brazil, in the Spanifh Eaft 
and Wefl: Indies, on the coaft of Afiica> and ii 
Upper Hiingary, where the mines have remainod 
unexhaufted for ten centuries. Peru and Meaco 
abound with gold in a variety of forms. It is met 
with in the fands of rivers and mountains. Some 
rivers in France, as well as in this country, contaiJi 
gold in their fand. It is alfo found in the fiffuresc^ 
rocks, imbedded in hard ftones. Pieces of gold of 
feveral ounces, and even pounds weight, an 
fometimes found, but in general it is difFufed in & 
fmall pordons, and through fo large a quantity of 
fand, that the trouble of cxtra£ting it is fcarcdy 
repaid by the gains. In all parts of the world, pir- 
ticularly in Europe, gold is molt frequently fouod 


Chap. 33.3 Gold Mines in Scotland. . a55 

- in ftrata of fand^ in which it feems to hare been 
cJcpofitcd by water. Gold mines were once wrought 
in Scotland, and it appears upon record that forty- 
: eight thoufand pounds (lerling of this gold was 
: coined in the Scotch mint. It is now a general 
: opinion among mineralogifts, that there are 
\ Icarcely any fands entirely free from gold, and 
; ivhich, by accurate examination, cannot be made 
I to afford more or lefs of that fubftance. 

Confidering that gold has no attraction for ful* 
phur, and very little for arfenic, which are the ufual 
mineralizers of metallic bodies, it is not furprizing 
that it fhould be ufually found in a feparatc and 
nearly pure ftate. The metallic bodies, with which 
it is alloyed in a ftate of nature, feldom conftitutc 
any confiderable part of its weight \ they are gene- 
rally either filver, copper, or iron. Gold, however, 
is fometimes mixed with martial pyrites, and is 
ibmetimes contained in an ore, which is a mixture of 
lead, filver, and iron^ mineralized by fulphun In 
thefe cafes the prefence of gold is not known by the 
appearance of the mineral, and can only be difco- 
vered by roafting, and fubfequent fufion with fuch 
matters as are capable of vitrifying the earthy and 
martial fubftances'. The addition of lead is alfo 
ufeful^ which unites with the gold, and carries it to 
the bottom of the mafs. The gold is eafily ob- 
tained free from the lead by the procefs of cupella- 

In order to feparate gold, when in ife native ftate, 
from the earthy and ftony matters in which it is con- 
tained, the following procefs is employed : When it 
X is 

(1^6 ^uariaim. [Book VI* 

U contained in Tandy the lifter particles of die 
latter are waJhed away by water, and the remain- 
ing matter, which may prove fo heavy as not to be 
ieparaced from the gold without danger of lofing 
fome of the precious metal, are amalgamized, hj 
being ground with mercury, in the fanfie manner as 
has been mentioned in the extraction of Clver. If 
the gold is mixed with ftones of conliderable bulk, 
it is neccflary that they fliould be redticed to 
powder in order to render them fufficiently light 
to be walhed away. The mercury is alfo feparatcd 
from gold in the fame way as from filver; as much 
as poffible is feparated from it by prefTure in bags of 
leather, and the remainder by heat. 

All the imperfeft metals may be abftra£ted frooi 
gold by cupcUation ; but in order to ieparate 
filver from it, other proccfles muft be employed. 
The beft of thefe is called quartation, becaufe the 
gold muft not exceed thcfourib part of the weight 
of the mafs fubmitted to trial The gold, therefore, 
muft be firft mixed with three times its weight of 
Clver, the effeft of which is, that the particles of 
gold are removed to fuch a diftance that they can- 
not proteft the filver from being affced on. The 
mafs of gold and filver being then beaten out into 
thin plates to increafc the furface, are expoied to 
the aftion of aqua fbrtis, which diflblves the filver, 
and leaves the gold in a fpongy mafs -, this is walhed 
two or three times with aqua fortis, and then ex- 
pofed to heat in a muffle *, to recover its metallic 

• A fmall earthen oven made and fold bj the crociUc 


^Chap.*33-] The T&ucb^one. f:^^j 

brighcnefs. When filvcr is thus fcparatcd by aqua 
£brtis, a minute portion of the filvcr is apt to ad- 
here to the gold^ and, therefore, when it is an objeft 
to ha^e the gold perfcdly pure, it is proper to fub- 
mit it to the aAion of aqua regia, which diflblves 
the gold, aiid converts the filver into luna cornea, 
which is precipitated to the bottom of the veffcl* 
When it is intended to feparate filver by aqua regia, 
the proportions of the metals muft be reverfed, 
and as the gold is to be difiolved, it muft be three 
times the weight of the filver. 

In this way gold may be obtained quite pure % 
but the goldfmiths find a difficulty in obtaining it 
perfcftly du6tile. To have it foft and tough^ it 
muft be melted with a ftrong heat, and afterwards 
tooled very (lowly. 

In applying faline fiibftances to gold, it is found 
that none of the acids, feparately employed, either ill 
a fluid form or in that of hot vapours, produce the 
leaft efieft on it in its metallic ftate. Upon this de- 
pends the trial of gold by the lapis lydius, or touch- 
ftone, which is of a dark colour and pretty fine grain, 
but when polifhed has fufficient roughnefs, ' fo that 
when the metal is rubbed over it a mark is left, which 
mark will be afiefted by any of the common icids, 
aqua fortis for inftance, in propordon to the impuri- 
ties the metal contains, but not at all if the gold is 
perfcftly pure. 

Goldfmiths ufe likewifetwo fet;s of needles, one for 
filver and the other for gold, when they want to exa- 
mine the finenefs of difierent parcels. The fees of 
needles for gold are alloyed with different proportions 
Vol. II. S of 

^$% Trial of Gold iy the tauchfime. * ^Book VL 

of copper'; one is made with twenty-three parts of 
gold to one of copper, another with twenty- tiw 
parts of gold to one of copper, and (b in proper* 
tion. When thty have a piece of gold to be tried, 
they firft examine its colour to detemciinc what 
quantity of alloy it contains. To know diis Ac 
better, they mark the touchftone with it, and ifaca 
make another mark with the needle, which the* 
think to be of nearly fimilar purity. Thus tbcy 
compare them; and after this, to be certain that the 
metal is gold, they apply to the mark on the (tone 
a. drop of aqua fortis. If it iS copper tinged wiin 
2inc, or any other imitation of gold, the aqua hm 
immediately diflblves it. If it contains gold and 
fbme other metal, it diflblves the other metal, aod 
leaves the gold, • 

, The only (aline fluid which diflblves gold in h 
metallic flate is aqua regia, or a mixture of the 
fiitrous and muriatic acids. It is prepared varioos 
ways: ift, By mixing the two acids in their pure 
ftatc; adly. By adding common fait, or ial am- 
moniac, to aqua fortis, and then diftilling the mix- 
ture. A part of the nitrous acid decompofcs 6t 
muriatic ialt, and detaches the muriatic acid, whkb 
rife$ with the remainder of the nitrous acid, and 
thus an aqija regia is produced. 3dly, By mixii^ 
a foludon of alum with nitre and common Ialt, iE 
which cafe the vitriolic acid of the alum difengagp 
the nitrous and muriatic acids by its fupcrior atnac* 
tion for their bales. 
' It is ufual to make aqua; regia by difTolvingfil 
ammoniac ki about four times its weight of ftroog 


Chap. 330 Ojerntim of Aqua Rtffxi ixphined^ 259 

nitrous acid \ but the fefults of experiments or ope-p 
rations vary confiderably atcording to the propor- 
tion of the ingredients made ufe of. 

The theory of the operation of this conipound 
acid.does not fecm difficult. In the courfc of this 
work it has been more than once remarked, that 
the eafy folution of metallic matters in acids 
does not depend merely on the degree of attradlion 
'which exifts between the metal and the acid, but 
alfo on the eafe with which the acid parts with 
oxygen to calcine the metal. From this caufe it 
happens, that the nitrous acidj which has much lels 
affinity with metallic matters than the' vitriolic or 
muriatic, diffolves them more readily than either 
of thefe. Aqua regia, however, confifts of the 
acid which has the ftrongeft attradlion for metallic 
bodi^, and alfo of that which mofl: eafily parts 
with oxygen, and the union of thefe powers pro- 
duces the efFeK5t of folution. That this is the true 
explanation of the folution of gold in aqua regia 
appears from feveral circumftances^ for gold, prc- 
vioufly .reduced to the ftate- of calx, that is, furnifh* 
cd already with a quantity of oxygen, is eafily dif- 
folved by muriatic acid, and gold, in its metallic 
ftate, is diffolved by the oxygenated or aerated mii- 
riadc acid, and forms with it the fame fait which is 
ufually obtained by the mixed acid, or aqua regia* 
The muriatic acidj therefore, is the true folvent of* 
gold, and the addition of nitrous acid has no other 
cfieft than that of furnifhing oxygen, fince the 
fame efFeft follows when the neceffary quantity of 
oxygen is previoufly added either to the gold or the 
Si muriatic 

a5o ASiion of Aqua Regia explained. £Bdok VI. 

muriatic acid. Gold, precipitated Scorn aqua rcgb 
by alkalies, and thus reduced to the calciform fiao^ 
is foluble even in the vitriolic and nitrotis acids. 

The addition oFwater tothe vitri<^c acidenabksir 
to diflblvc iron exaftly on the fame principle thattfat 
addition of nitrous acid to the muriatic enables Ac 
latter to diflblvc gold. The concentrated TitrioEc 
acid has no a£Hon on iron without the affiftance id 
heat 5 but by a proper addition of water the proccS 
goes on, in the ordinary temperature of the atmo- 
Iphcre, with confiderablc rapidity- The Water fcr- 
niifhes oxygen to the iron, and its other compoiffl^ 
part, hydrogen, is fct at liberty ; and that the nknxs 
acidj in the aqua regia, anfwers the purpofc of faf^ 
nifliing oxygen to the gold, is proved by the dih 
engagement of nitrous gas. 

The folntion of gold in aqua regia, when fiit 
made, is always yellow, confiderably cauftic, cor- 
rodes animal matters, and tinges them of a deep 
purple colour. When applied to the furfecc cf 
marble, it tinges it of a violet colour. This coteir 
is produced by a precipitation of the gold, in codc- 
quence of the fuperior attradKon of the calcareo'^ 
earth for the acid. 

The folution of gold may be made, by eautioa 
Evaporation, to afford cryftals of a beautiful top« 
or yellow colour. Gold may be in fbrnc meafet 
volatilized by repeatedly diftilling it with aqw 
regia; fome of the gold rifes with the acid intotk 
neck of the retort in the form of longQcnder brow 

Chap. 33*] Fulminaiing Gqld. a6i 

Gold is precipitated from its folutlon by a great 
variety of fubftances, but its appeafances are very 
various, according to the nature of the matter em- 
ployed. Lime and magnefia precif^itate gold in 
the form of a yellowifh powder, and thb^^xed alka- 
lies have the fame efFedl. Volatile alkali produces 
a more quick and copioys precipitation, and forms 
the remarkable compound, known by the name of 
aurum folminans, . the nature of which has been al- 
ready intimated in a note under the head of ignition, 
I fhall in this place, however, add a few obfervations, 
l?vhich may tend ftill further to illuftrate its nature. 
In the firft place, it appears that the fulminating 
gold is a compound of about three parts of that 
metal with one of volatile alkali. Secondly, 
Fulminating gold, expofcd to fuch a heat as is fuffi- 
cient to feparatc the volatile alkali, without fctfing 
fire to the compound, lofes its fulminating property. 
The fame cfieft is produced by fubmitting the au- 
rum fulminans to the aftion of concentrated vitrio* 
Jic acid, melted fulphur, aether, or any fub- 
ftance 9apable of abftrafting the volatile alkali by 
fupcrior affinity. Thirdly, When a few grains of 
'aurum fulminans are detonated in copper tubes, the 
cxtrejnity of which is plungqd beneath the mercury 
of the pneumato-chemical apparatus, azote is dif- 
cngaged, a few drops of water are produced, and 
the gold is reftored to its metallic appearance. M. 
Berthollet, the inventor of this experiment, con- 
cludes, that the volatile alkali is decompiofed, ahd 
that while one of its component parts, hydrogen, 
unites with the oxygen of the c^ of gold, and 
S 3 forms 

a62 Fulminating Gold. [Book VI. 

forms water, its other component part, azote, i 
capes in the form of gas. The readinds wt 
which fulminating gold explodes leems to depd 
on the tendency which the hydrogen of i& 
.alkali has to unite with the oxygen of the mctai* 
calx, which tendency the weak atcra6tionof thegoU 
for the oxygen on the one hand, and/the azote 6f 
hydrogen on the other, are fcarcely fuffidcntP 
counteraft. Whenever the balance of pow 
among thefe ingredleiits is difturbed, which hf 
pens from a moderate increafe of heat, or Vioh: 
friftion, the hydrogen and oxygen unite and fori 
water, the gold is reduced, and the azote dbpcs 
in the form of gas, occafioning a violent apt 
fion, ^ I 

When gold is newly precipitated, Margraffi- 
forms us, that it may be re-diflblvcd by the volack 
alkali, or, much more readily, by the PruffianaM 
Alkaline falts precipitate gold in the form of aalxj 
but inflammable fubftances precipitate it in tbcfljf- 
tallic form. The moft fingular effeft of inflamimbk 
fubftances upon thefolution of gold is thatoftif , 
vitriolic ather, though it does not entirely k^ 
the gold from the acid. If into a phial of diffi^ ' 
water a fmgle drop of the folution of goldisinn^- 
duced, the water will become of a fine yellow colou:; 
add to this a quantity of vitriolic aether, which w3 1 
float uppermoft, and remain colourlefs, no fcnfil* 
change being produced ; by 'fhaking the mic^' 
however, for fome time, and then allowing i^^ 
reft, the yellow colour in the Ipwcft part of thepk» | 
will leave the water, and- rife up into the «rf^' i 

Chap; 33.] Purple Powder of CqlJiiis. a^J 

By repeated agitation^ in a little time the arthtfr will 
draw up into it the whole of the gold, fo as to leave 
the liquor at bottom perfeftly colourlefs. It would 
be erroneous to conclude from this experiment, that 
sether is a folvent of gold j it does not diflblve it, 
but attrafts the folution merely by its affinity for 
acids. Though the aether afts primarily on the 
acid, it at length feparafes the oxygen from the 
calcined gold, and precipitates it in its metallic 
ftate. All the fubtile aromatic oils have a fimilar 
effedV, but do not a6l fo readily as £ther. 

As thefe inflammable fluids have no aftion on 
the folutions of other metals, this procefs may be 
uled as a means of refining golds for the acid con- 
taining gold is imbibed by the inflammable fluids 
while that part of it which is combined with any 
other metal remains behind. 

Almoft all metallic fubftances precipitate gold 
from its folution in aqua regia. Mercury and cop- 
per feparate it in its fhining metallic form; lead, iron, 
and filver, precipitate it of a deep and dull purple 
colour. A plate of tin, plunged in a folution of gold, 
feparatcs the perfeft metal in the form of i deep 
violet powder, called purple powder ofCaffius, 
v^hich is ufed in painting, in enamel, and in porce* 
lain. This powder coofilb of the calces of gold 
and tin in combination, and is capable of commu- 
nicating a fine purple colour to glafs. The folutioji 
of green vitriol precipitates no other metal but gold, 
and the gold proves of uncommon purity, and of a 
very deep colour. Gold in its metallic ftate is in- 
capable of uniting with fulphur alone^ but if a piec;e 

S4 of 

t^ GoUen Calf rmitredfelukh. [Book 7L 

of gold is dropped into a folutkHi of hq>ar fulfduirii^ 
efpccially if die latter is prepared with equal parts of 
folphur and alkali^ the gold diflblres vnx}\ fbme 
ebullition^ and forms a mais, wbichdiflblves in water 
like the combination of alkali and crude antinMny. 

Stahl fuppofes that this procefs was ufed hj 
Mofes to render the golden calf^ adored by the 
Ifraclites, foluble in water. 

But though gold will not unite with fulphur» k 
may be purified by means of it, the fulphur unitii^ 
with the metals with which it is alloyed. With this 
iriew it is ufual to heat the gold with crude andmo- 
hy, in which ftate the fulphur is more fixed that 
yrhen applied in a feparatc ftate. In this procefs, 
however, the gold combines with a portion of 
antimony, which tniift be afterwards driven offf^ 

There are fcarcely any metals with which goU 
will hot unite. When boiled a fhort time with 
mercury, it forms an amalgam which is gritty and 
rigid at the firft, but which becomes by grinding 
more foft and tender; this is often made ufc offer 
gilding the furfiice of filvcr and copper, as was more 
particularly mentioned when treating of die latter 

Gold readily unites with zinc, and produces a mix- 
ed metal, whiter than might be expefted from the 
quantity of zinc which is employed; this alloy, made 
with ecjual parts of the two metals, is remarkably 
fplendid, is of a fine grain, and is not liable to tarnifh : 
■ on account of thefc properties it has been recom- 
^mcudcd in conftrufting the mirrors of tclclcopcs* 
• ' ' a. All 

Chap* 330 Standard of Gold Coin. 265 

All the metals, except filvcr and copper, take 
away the duftjlity of gold, but none more remarkably 
than tin, a grain of which added to a thoufand of 
gold is faid to depriMP it entirely of duftility. Cop- 
per; is commonly ufed to alloy gold, as filver render^ 
it very pale. Copper rather heigbtiens the colour 
pfgoJd, but inclines it to red. 

Goldfmiths denote the finenefs of gold by the 
1 word carrat. It is fuppofed to be divided into 
t twenty-four parts, called car^rats ; and gold, which is 
I quite frtt from alloy, is faid to be twenty-four car- 
rats fine; that which contains one twenty- fourtI| 
pf alloy is called gold of twenty-three carrats ; 
that which contains two twenty-fourths, of twenty- 
pNo carrats, and fo on. In England, the ftandaixi 
of goW coin is twenty- two carrats fine gold and 
two carrats of alloy, which latter is half filvcr and 
Jialf copper. The French, Spanilh, and Flcmilh 
^old are nearly of the fame finencjS. 


C 26S 3 [BookVI^ 

Chap. XXXIV. 

P L A T I N A. 

tlatural.Hifiory of this curious MetaL-^Iis Properties,— ^Tbe m^ 
ponderous Body in Nature, — Its Hardne/s and InfuJihility,^-»So» 
luhk only in Aqua Regia and oxygenated muriatic Acid,^^ 
Its Union nuith other Metals,— -CruciBles formed of it.^-^Might 
be applied to 'various Ufes ns^hich no other Metal catean/wer, 

IN the beginning of the year 1749, the firft Ipe- 
ciinen of this metal was brought into England 
from Jamaica. It was faid to have been originally 
hf ought from the Spanilh Weft Indies, and it is ftiU 
almoft exclufively found in the gold mines of Spa- 
nifti America. It is brought over in the form of 
finall fmooth grains, irregularly figured, with round 
edges, and is often mixed with ferrugincous {and 
and grains of quartz or cryftal. ' The grains of 
platina ^re whiter than iron, but lefs fo than filver, 
and their fiat form is probably owing to the pref- 
furc they undergo in the mills in which the gold is 

In confirmation of this opinion, fmall particles of 
gold and mercury are ufually found mixed with the 
grains of platina. In the ftace in which they are 
brought over, they fall fliort of the weight of gold, 
but by purification, which is performed by wafhing 
with the muriatic acid, and by expofing them for a 
long time to the heat of the moft violent furnaces, 
which, however, are faid to be infufficient to melt 
5 thcm^ 

Chap. 34.] Natural Kftory cf Platina^ a6y 

them*, they exceed it. The fpecific gravity of 
gold is about nineteen times that of water, whereas 
platina, which ftill contains fo much iron as to ren^ 
der it magnetical, is upwards of twenty-one times 
the weight of that fluid. It is extremely difficult to 
free platina from the laft portions of iron, but fomc 
minute particles, which have been fufed by the focus 
of a burning glafs, and fo far purified as not to be 
attracted by the magnet, appear to exceed twenty- 
two tim^s the weight of water. 

Platina is, perhaps, the moft perfeft of all the 
metals. As it fo confiderably exceeds even gold in 
weight, it is therefore to be confidered as the moft , 
ponderous body in nature. 

It has feveral properties in common vnth the 
tnoft ufeful of metals, iron. In hardnefs it ap-' 
proaches to that metal m the ftate of ftecl; and in 
jnfufibility it exceeds it even in the ftate of foft irons 
it alfo ponfiderably refembks iron in appearance, 
and it is the only metal, befides iron, which has the 
property of welding. 

Platina refembles gold in being foluble only in 
aqua regia, and it even requires a larger quantity 
of that compound acid for its Iblution than gold. 
The folution is of a deep yellow or reddifh coloun 
The proportions of acids beft adapted to the folu- 
tion of platioa arc, equal parts of the nitrous and 
muriatic acids; but the folution does not then take 
place with rapidity. This compound is very cor- 

* This is the opinion of the generality of mineralogies ; 
but my friend and chemical preceptor. Dr. Higgins, aiTured 
pCf he had melted platina in his furnace. 


268 Aaion ofS^Une Matters on Platina. [Book VI. 

rofive, and tinges aninfial fubftances of a blackilb 
brown colour. 

The vegetable alkali added to this folution onlf 
o'ccafions the precipitation of a part of the metal in 
the form of a fparkling powder, which is foluble in 
a large quantity of water. A very remarkable clr- 
cumftance is, that the foffil alkali does not produce 
any precipitation, unlefs added in very confiderable 
quantity. Common fal ammoniac, applied to the 
folution of platina, produces a precipitation like the 
fixed vegetable and volatile alkalies. It fcparates 
fi part of the metal in a fparkling red powder, and 
a part remains diffolved, which it cannot fcparate j 
but if vegetable alkali is added after the fal ammo- 
niac, it precipitates the reft of the platina ; and on 
the contrary, fal ammoniac, added to die foludon 
containing the remainder, which the fixed alkali 
could not feparate, precipitates it, fo that by adding 
both the vegetable alkali and fal ammoniac, the 
whole of the platina is feparated. Platina, like 
gold, is alfo foluble by the oxygenated muriadc 

The fubtile inflammabje fubftances, as Ipirits of 
wine and aromatic oils, do not produce any fepara- 
tion from the folution of platina in aqua regia, as 
they do from that of gold. Tin precipitates it, but 
the precipitation is not purple like that of gold. 
Mod of the metals precipitate platina, but it docs 
not in general fall down in the metallic ftate. The 
precipitation of platina, from its folution by fal am- 
moniac, affords a method of feparaung this metal 
from the gold which is mixed with it, as the goW 


ChapJ 34-] Union of Platina^hk ciber MeUls. 169 

IS not feparated by the addition of thax lak^ if, oa 
the contrary, we wifh to precipitate the, gold, and 
leave the platinain folution, this may be effedod by 
jai martis* , 

The precipitates ot platina may be reduced to a 
metallic button, by heating them mth the comervoit 
fluxes; but thefe cannot be rendered malleable 
unlefs they are completely fofcd, which can fcarccly 
be cffefted, iinlcfs with thfc heat of the moft pow-r 
erful burning glafles. 

A mixture of copper with platina forms a o-icr 
callic body of intermediate colotir and great den* 
fity, ib that it receives a very fine polifh. A mix- 
ture of three or fijur parts of copper to one of pla- 
tina pofiefled all the above properties in great per- 
* ibaion, and was not tarnifhcd in the air in the Ipacc 
often years. With iron it alio produces a com- 
pound of great denfity, which is hard, ftrong, and 
tough, and admits of a good poliQi. Moil: nnetab 
increafe the fufibility of platina fo much, that it may 
i>e melted in ordinary fiirnaces. 

Gold is greatly injured in colour by a mixtw* 
\c>f platina, and becomes of the colour of beU mttdl 
by the addidon of no more than one twenty-fouitk 
part, though half that quantity produces little 

Platina with bifmuth and tin forms alloys, which 
are brittle, but eafily fufed. Platina and lead unite 
very well by fufionj but the duftility of the lead is 
deflSroyed, and the compound quickly tarnifhes on 
efpofure to air« Pladna. partly dcflxoys the du£ti- 

ayo Crudhki 6f PlaHna. [BookTL 

firir of filver, augments its hardnefs^ and impabfi 

Platina completely rcfifts the a<5l:k>n of merer*, 
with which it (hews no difpofition to uoicc 0:) 
this account it does not mix itfelf with the goli 
which is extraded from the fubftances with wlaii 
it is mixed by amalgamation. 

From the extreme infufibility of platina, it k 
excellently fitted to contain other matters, whidii 
is intended to fubmit to a violent heat. M. Achac 
fucceeded in making crucibles of platina^ by ihs^ 
equal parts of platina, white arfenic^ and yegetahk 
alkali. This matter, when cooled, was reduced o 
a powder, and rammed into a mould. A flra; 
heat, quickly raifed, and continued for fome cme, 
ftjfed the mafs, and after difDpating the arfcaicail 
alkali, left the platina in the dcfircd form. 

Platina, when thoroughly purified, by coftion ia 
the muriatic acid and precipitation from aqua r^ 
may be fufed into a mafs nearly astnalle^le as ^ 
iron. This property, united to thofe of vciH 
acids, its great infufibility, and welding, fccm wil- 
der platina applicable to purpofes which no otto 
metal is capable of anfwering. 


Chap. 35-] [^70 

Chap. XXXV. 


Ignition and Comhujiion defined.'^^Acidi formed fy the Comhufiiott 
of inflammable Subftances. — Flame, bow produced^-'-'The Obje£i 
of the pre/ent Inquiry limitedj-'^What Subjiances are commonly 
termed inflamtAable, 

THE difference between ignition and combuC- 
tion confifts in this :— All bodies which can 
fupport a certain degree of heat, without the deftruc- 
tion of their texture, emit light, and this is called igni- 
tion ; but combuftion or inflammation is a property 
which belongs to fuch bodies only as arecapable,when 
placed in proper circumftances, of augmenting their 
own temperature. Simple ignition produces no per- 
manent change in bodies, but combuftion entire- 
ly alters the properties of fuch as have undergone 
that procefs. From being mild and nearly infolublc 
in water, they become acrid, pungent, and ex- 
tremely foluble, and are converted into acids, which 
differ according to the fubflance, by the inflamma- 
tion of which they were formed. The terms com- 
buftible fubftance and acidifiable bafis ar^, there- 
forei in the French nomenclature, iynonymous. 

In the elementary part of this work it has already 
been remarked, that inflammation is the difengage- 
ment of the matter of heat or caloric contained in 


s j% Inpmmaile SubfianceL [Book Tf. 

vital air or oxygenous gas, in confcqucncc of dr 
bafis of this gas becoming combined with odicr 
bodies. All bodies, therefore, which are capafak 
of decompofing vital air, change a quantity d 
latent heat into ienfible heat, and are iaid to be b- 
flammable from the light and heat which feem to 
proceed from them, but which, in fafl:, arc dcrivoc 
from the oxygenous gas, which is one of the com- 1 
ponent parts of the atmofphere. 

The neceflity of the prefcnce of air to combuftHS 
is (Irongly maintained by M. Lavoifier, and an eiqjc- 
riment related by him (to the latter part of which I 
feel fomc reludance to give an unqualified a&ot) 
feemsj indeed^ to prove it to be e0encial io all caib. 
He fucceflively placed a quantity of phoiphoruSyoT 
fijphur, and of gunpowder, under the receiver of a 
wr-pump, making as perfect a vacuum as the m- 
chine would admit. He then threw the focus ol i 
lens of eight inches diameter on die dif^rcnt fab- 
ftances, which were not at all ignited> only bubhkd 
tip> and at length fublimed. The gun|K>wder wis 
dccompofed, the fulphur of it only fubliming, sod k 
neither took fire nor exploded. 

In ordinary language, no bodies are faid to be 
infiammable but fuch as burn eaClyi or which, ia 
other wofds, are capable of decompofing vittliir 
in the diluted ftate in which it exifts \n .the atOBO- 
^here. In a more ftrift fenfc, however, the pro- 
perty of inflammability bek>ngs to other bodies, 
though they ppfiefs it in a leis eminent degree; as 
to zinc, ^icb> when made cxtremdy hoc, bur» 
with a dazzling white lights and to iFoa> wfaicby 


Cfiap.jj.y Comhttfiim of Metals. • '' ^Y^' 

"^hen heated to a proper degree, buttis in pure oxy- 
genous gas. The oxygenation which all metals^ 
except the perfeft, undergo from the conjoined ope- 
ration of heat and air, are alfo to be confidered as 
cafes of flow combuftion. In fhort, all fubftances 
may be laid to be inflammable which are capable, 
in any circumftances, of decompofing vital air, or 
"whiclr have a flrronger attradtion for the bafe of that ' 
stir than that bafe has for caloric or heat 

In all inftances of inflammation a certain degree' 
of heat is neCeflkry to begin the procefs. Diffx^rent 
inflamihable fubftances require diHereht degrees of 
heat &r this purpofe. Phofphorus is fully inflamed 
at the heat of 86^ degrees of Fahrenheit, but 
undergoes a more gradual combuftion at' a much 
lower temperamre. Sulphur requires much more 
heat than phofphorus, and charcoal fliU more thaii 
lulphur. There arc fome fubftances in nature 
Mrhich are fo combuftible, or have fo ftrong an at- 
traftion for oxygen, as never to hive been found 
uncombined with that principle ; of this kind are the 
unknown bafes of the boracic, fluoric, and mtirianc 

Though an acid lis always formed by the coni-- 
buftion of every inflammable fubftance, this fafl: 
was never attended to, or at leaft never properly 
apprehended, till within thefc few years. In ordi- 
nary cafes, indeed, this'circumftaijce was likely to 
pafs unobferf ed ; for the acid produced by the in- 
flammation of charcoal, which is the eflehtial in^ 
grcdient^in aH kihds^ of fuel, is^-fhc carbonic acid 

Vol. II. T gas. 

174 Comhujim vfithout iHamf. [Book \1 

g^s, or fixed alfj which efcapcs without leaving anr 
traces. In the combuftion of fulphur alfo, the 
acid Si|cs off in fumes, unlefs coUedled by a paitioh 
l^ proccfs, which was defcribed in treating of the 
fulphuric or vitriolic acid. The phofphoric adii, 
however, is a concrete body, and therefore cannot 
eafily be overlooked. When inflammable bodio 
are imited with oxygen they become acids, asl 
having no longer fufiicient attra&ion for oxygen lo 
decompofe vital air, they lofe their inflamni^)iiitT. 
According to the old chemical doArine, the heacaof 
light afforded by inflammable fubftances were fiip- 
poled to derive their origin from the difengageineai 
ofphlogifton; but, according to thcdodrincofM. 
Lavoifier, the vital air of the atmofphcrc is the 
repofitory of light and heat, frorn which a]l ardfr 
cial fupplies are derived, by means ofinflammabk 

There is one ftriking difference among inflam- 
mable fubftances, which is, that fbme bum vit!^ 
and fome without flame. Of the former kiixUt 
oils, Ipirits of wine, and moft others $ to the Ukt 
kind belong the different fpecies of charcoal, aad 
fuch of the metals as ^e inflammable, Thcca* 
of this difference is, that fome inflammable bodies 
afford an inflamrnabk vapour, the burning of whii 
produces flamef others are endrely -fixed, and p 
duce no fuch vapour. The vapour, however, asf 
rifes is not wholly confumcd; the reafon of whidiJ^ 
that the air. does not find accefs to the center of tt« 
column of vapour. Flame i&' a hoUow cone to* 



Chap. 3^.] Ihjlamnutlle Subfiances. *47j 

rounding a folid cone of vapour. In lafge fiames> 
the furface on which the air a£bs is lefi in propor^ 
tion to the quantity of vapour than in fmadlD^es> 
hence the quantity of fmoke and foot produced by 
Ixnall fiannes is propbrtionably leis than that produced 
by large ; for fhioke and foot are only that part of the 
vapour which is unconfumed. Upon this principle 
it happens that more light is afforded by candles 
with a fmall wick, ' in proportion to the quantity 
t)f inflanimable matter confumed, than by thofe 
^ith a large wick. The fame end is anfwered by 
extending the wick in the form of a ring, and leav- 
ing room for a current of ^r in the middle, as is 
done in the patent lamps *. 

I^ treating of inflanmiable fubftances it will 
be netJeffary to confine the inquiry to thofe which 
poffefs this property in a more remarkable degree. 
I (hall, ^therefore, firft treat of the fimple inflam- 
mable fubftances, phofphorus> fulphur, and coal^ 
or the cirbon of the French philofophers. Hy- 
<irogen, or inflammable air, has already been de- 
fcribcd under the head of elaftic or aeriform 
fluids. With refpedt to the compound inflammable 
fubftances, i'uch as oils, refins, fat, &c. it will be 
found that they confift of different' proportions 

* Thi5 fii6l was previoufly explained in the chapter on 
ignition, in the fecond l)ook. The inflammable part of the 
vapour is fb completely. conAimed in Argand^s lamps, that if an 
alembic is fixed to the top of the lamp« the matter condenfed 
is altogether watery 

•■^ T a aad 

^j6 trfiammahk Syipmas^ [Book VL 

and ftates of coiobination, of carbon, hydiogtob 
and oxygen. The infkmmable matter of charcoal 
and coke confifts of carbon only; pitcoal and woodl 
in then* erode ftatCj contain alio ibme hydipgo^ 
which is driven ofF» together with water and cii^ a 
the procefs of charring. 


Chap, 36.] [ ^77 3 

Chap. XXXVl. 

fh/phorus tfKmkeL — Light frtm putre/cent SubJtancis.^^Cttritut 
Fa^s.-^Ligbt from tiff Sta H^Mer, ^c^^B^kgniun Stmu*^^ 
BaUkuittV Phf>/pbenu. — Fko^bwus rf Hombfrgw^Fjr^bvri. 

PHOSPHORUS* is a fimplc copnbuftiblc 
fubftancci which was unknown to chemifts 
till 1667, when it was difcovercd by 'Brandt, a 
German chemift, who kept the proccfs a fccrct ; 
foon after Kunkel found out Brandt's method of 
preparation, and made it public. It has ever fince 
been known by the name of KunkeFs phofphorus. 
The appearance of phofphorus is that of a tranipa- 
rent fubftance, of a colour inclining to yellow, like 
clear horn J it is fpecifically heavier than water, is 
tougb> and cuts like bees* wax, and like it ^melts 
with a gentle heat into a traniparent fluid. With 
this heat it may be melted in watery but if the fame 
degree of heat is applied in the open air, it melts^ 
takes fire, and burns, producing a bright white 
flame with intenfe heat* Phofphorus (hcHi|d be 
handled with great caution, ^ ihould any of it 
adhere ,to the fkin, or get under the nsuls, the heat 
of the human body is fufiicient to infldtfte \u The 
procefs for obtaining phofphorus from bones was 
defcribed in treating of thephofphoricacid,. 

• Derived from the Greek—" ATubftaoce afforiing ligbt.'» 
T I When 

ayS Comhuftm ofPboffborus. [Book VI. 

When a quantity of phofphorus is burnt in fmall 
pieces under a bell, the phofphoric acid attaches 
itfelf to the internal furface of the bell, in the form 
of a downy mafe. Tiiis concrete acid has fo ilrong 
anattraftion for water as to imbibe it from the 
atmofphcre wilh aftoniffiing rapidity, till it is con- 
verted into a liquid confiderably more denfe^ and* 
of greater fpecific gravity than water. 

From the experiments detailed in M. Lavoifier's 
elementary work on chemiftry, it appears that one 
pound of phofphorus requires one j)ound eight 
ounces of oxygen gas for its combuftion, and that 
two pounds eight ounces of concrete phofphoric 
acid are produced. 

The phofphoric acid may be obtained by three 
other proceflfes befides this. If phofphorus is melt- 
ed in hot water, and a ftream of vital air pafled 
throughit, it becomes oxygenated. The fame thing 
Happens by plunging ic in nitrous acid, from which 
k abftrafts the oxygen. It may be alfo acidified 
by fimple expofure to thc.atmofphere, which ough( 
not at the time to exceed the temperature of fixty 
degrees, from the danger of inflammation i in this 
fituatibn, by a gradual cornbuftion, it attracts the 
oxygen of the atmofphere^* and^ecomes converted 
into an acid. 

The cauftic fixed alkalies diflbhre phofphorus by 
the afliftance of heat. During this combination a 
fetid gas is disengaged, which has the fingular pro- 
perty of exploding as foon as it comes in contact 
with atmofpherical air, and ftill more rapidly by 
cont^ft with vital air. 


Ch^pl 36.] Natural tJifiory of Pbojfborus. 279 

: The phofphoric acid forms pecuFuur falts with the 
alkalies and fome of the earths^ and h^ the pro* 
perty of corroding glafs. With the mineral alkali 
ic forms a fait, the tafbe of which is lefs unpleafanc 
than that of other neutral faks, and which is weU 
calculated to anfwer the purpofes for which neutral 
felts are ufcd in medicine. The phofphoric acid' 
2i£t$ only on a fmall number of metallic fubftance^^ 
but readily diflblves, in its fluid ftate, iron, zinc, and 
copper, with which it forms falts not cryftallizable. 

Phofphorus feems to be aliTwft univerfal in the 
animal kingdom, and is alfo found in fome minerals, 
«SH in a Very minute proportion in moft vegetables. 
The bones of animals are a true phofphat of lime, 
or an earthy fait compofed of phofphoric acid and 
calcareous earth. The urine alfo contains a confi- 
derable quantity of phofphoric acid, chiefly com- 
bined with volatile alkali, but partly alfo with calca- 
reous earth. This compound fait, afforded by the 
evaporation of urine, was formerly known by the 
names of effential fait of urine, or microcofmic fait, 
Brandt, Kunkel, and MargraflT, and all chemifls, 
till lately, prepared their phofphorus from that fub- 
ftance, but it is now almoft entirely obtained from 
bones, which afibrd it more plentifully and with lefs 
trouble. Phofphorus does not yet feem to have 
been applied to any important ufes. 

From the remarkable eafc with which phofpho* 
rus is inflamed, feveral experiments may be exhi- 
bited by means of it, which appear like the cffefts 
of magic to perfons unacquainted.with the nature 
of this iubltancc. Thus, for example, if the outlide 
T 4 of 

i8o . Pbilo/opbical Magk. ^ [Book VI* 

of a bottle is ruhbed vitb phofi^rus^ and then 
furrounded with tow, and hot water poured into 
it, the phofphorus takes iire> and communicates 
the inflammation to the tow. If a ftick of phof- 
phorus is ufed to write on a piece of paper, or on a 
wall, a quantity of phofphorus is abraded, and, un- 
dergoing a flow combgftion, renders the ftrokes 
yifible in the dark, while in the light they can only 
be perceived to exhale a whitilh vapour. 

A fluid called liquid phofphorus is prepared by 
digefl:ing fome phofphorus in the heat afforded by 
horfe dung for two days, in oil of cloves, oil of tur- 
pentine, or any fimilar fubfl:ance. After diffolutipa, 
the oil will be fo impregnated with it, that when the 
phial is opened, it will appear luminous. Any 
thing moiilened wi^ this fluid will in the dark 
feem to be on fire. 

Many natural phenomena, which in the ages of 
fuperftition ferved to aftoniih and aflright mankind, 
have received a fatisfaftory folution from the dif- 
covery of the phofphorus pf KunkeL We learn 
from Fabricius ^b aquapendente, that three yoimg 
men at Padua, having bought a lamb, and eaten 
part of it on Eafter Day, 159c, feveral pieces of 
the remainder, which were kept tiH the day follow- 
ing, ibone like fo many oandles when cafually 
viewed in the dark. It appears by his account, 
that: the aftoniflimcnt of the whole city was excited 
by this phenomenoq, and a part of the flcffi was fent 
to him, who was profcfTor of anatomy, to be exav 
mined by him. He obferved, that thofe parts 
which were foft to the touch and tranfparent in 


Chap. 3^-1 Sufirftitims ^enrors^ ft8i 

candle lig^c wer€: the mofl: refpkndent. A philo- 
fopher of not lefs note, has furniflied i^ with a very 
pompous accou^it of a funilar phenomenon, which 
occurred at Montpelier in 1641* A poor cdd wo- 
man had bought a piece of flefh in the market, ia« 
texKling to make ufe of it the day following; but 
happening not to fleep well that night, and her. 
' pantry beii^ adjoining to her bed, £he obferved 
that a quantity of light proceeded from the meat, 
fo as tp illuminate ^moft the whole place where h 
hung. We may eafily judge of the terror and afl;o- 
niQiment of the poor woman herfelf, fince we find 
that a part of the Q^efh was carried, as a very extra- 
ordinary cufiofity, to Henry Duke of Conde, who 
viewed it with the ytipoft furprize for feveral 
hours. The light was as if gems were fcattened 
over the furface, and continued till the flefli 
began to putrify, when it vanifhed, which it was 
believed to do in the form of a crofi. 

The attention of a more philofophic age was 
direfted to experiments to afcertain the caufe of 
this light. Mr. Boyle found, that the light of rot- 
ten wood was extinguiihed in vacuo, and revived 
again by the admiflipp of ^r, even after a long con- 
tinuance in vacuo. The extindion of the light was 
notfo complete immediately on exhaufting the recei- 
ver, as.fome litde time afterwards. The wood was not 
much affefted by cbndenfed ^ir; but the light of a 
fhining fiih, when put into the condenfing engine, 
was rendered more vivid by that means. As air is 
therefore neceffary to combuftion, thcfe experiments 
clearly indicate, that this light is the effedk of a 
flow combuftion, or fomcthing analogous to it; 
x and. 

i82 Explanation of tbffe jlppiarancis. [Book VI« 

and, indeed, the experiments upon the phofphorusr 
of Kunkel have fince placed this matter beyond a 
doubt. The combuftion, however, in thefe cafes, 
is fo very flow, . that no change of air appeared nc- 
ceflary for the maintenance of this light, for it con-» 
tinued for a k>ng time, even though the wood wa9 
confined within a glafe hermetically fealed. 

To explain the caufe of this combuftion it ia 
only neceflary to repeat what has been juft flated^ 
(hat there exifts in every animal body, and in moft 
vegetables, a certain quantity of phofphorus. Thi^ 
principle, we have feen, is extremely a&ive, and has 
the ftrongeft tendency to unite with the pure part 
of our common air. During that leparation, there- , 
fore, of the parts of bodies, whieh takes place in an 
incipient putre&£tion, thefe phofphoric particles arc 
detached from thofc with which they are combined, 
and by the aftion of the air, a degree of combuftion 
takes place, but fo extremely faint, that light only 
is produced, without the leaft appearance of fenfible 

This ihort explanation of the caufe will, I flat- 
ter myfcif, correfpond with moft of the phenomena 
of this kind noticed by philofophers. Mn Boyle 
found that the light of rotten wood was in moft re- 
fpefts analogous to that of putrefcent fubfhnces. 
The light of the former, however, differed in fbme 
rcfpefts; it was prefcntly quenched with water,, 
fpirit of wine, and a variety of other fluids; but th^ 
light of fome fhining veal was not entirely quench^ 
by water, though its virtue was inftantly deftroj^ed 


Chap. 2^'} Luminous Jfpearance of the Sea^ aZj 

by Tpirit of wine*. The fame philofophcr was 
fomctimps difeppointcd in his experiments on 
fliining fiflics; particularly he obferved, that they 
failed to become luminous in cold and froftjr 
weather, which is cxaftly agreeable to the nature of 
phofphorus, fince its combuftion is exadiy. in 
proportion to tl}e heat which is applied to it. He 
remarks alfo in another place, that the light of. 
ftiining wood was completely cxtinguifhed by ex- 
tt-eme cold. 

Some bodies have a much greater tendency to 
produce this light than others. A foreign philo^ 
fopl^er remarked, that on opening a fea polypus it 
>yas fo luminpus as to ftarde moil of the peribns 
who faw it i the nails and the fingers of thole 
who touched it became luminous alfo. The light 
of the gjow worm, and other luminous infers, mufl: 
depend ypon fome flimy or fluid matter which they 
emit, and which has this tendency to (hine. There is 
a remarkable Ihell-filh, cilicd pbolesy which forms for 
itfelfholcsindiflfercntkindsof ftonc. This fifh illu- 
minates the mouth of the perfon who eats its and it 
is remarked, that contrary to the Jiature of other 
filh, which give light when they tend to putref- 
cence, this is more luminous the frefher it is, and 
. when dried its light will revive on being moiftened 
either with lalt water or frelhi brandy, however^ 
immediately cxtinguifhes it^. 

The luminous appearance of the fea in che night 
time cannot have efcaped the obfervation of an/ 

• Prhjf. Of. 565. t Ibii 567. 


5?84 iMtninausjffpearanceofibeSm. [BookVL 

pcrfon in the leaft converiant with that dement. 
The light occafioned by the dafhing of oars^ or by 
the motion of the waves by night, is extremely 
beautiful. Father BoUfzes, in his voys^c to tl^ 
Indies in 1704, remarked particularly the luminous 
appearance of the fca. The light was Ibmetimes 
fo great, that he could eafily read the tide of a book 
by it, though nine or ten feet from the furfaceof 
the watcn Sometimes he could eafily diftinguiffi, 
in the wake of the (hip, the particles which were not 
luminous from tiiofe that were. The luminous 
particles alfo appeared' of different forms ; fbmc 
jippeared like points of light, others like ftarsj' 
fome of them rafembled globes of a line or two 
diameter, and fome appeared as large even as 4 
man*s head ; they aflumed fquare afnd triangular 
as well as globular forms, and not only the wake 
of the fhip, but fiflies in fwimming, produced thefc 
luminous appearances. All thcfe phenomena he* 
attributes, and rigiuly, to the fat or putreicent 
-ftate of the water, and obfcrved, that when the 
wake of the fhip wa6 brighteft, the water was moflr 
clammy and glutinous. In fome parts of the fca, 
he faw a fubftance like yellow and red duft, and 
the failors told him it was the fpawn of whales which 
produced all thefe appearances*. Later experi- 
ments haye proved, that the luminous appearance 
of the fea entirely protceds from the putrefcent 
parts of marine animals f, 

* Friefi. Op. 572^ f Ibid. 576. 


Chap. 36.] Ugbts about the 'Beds of Sick Perfons. agj 

Human bodies, as well as thofe of other anU 
malS) emit light juft when thejr begin to putrify • 
and the walls and roofs of places in which dead bo- 
dies have often been expoled have been obferved 
to have a (limy matter depo^fited on them, which 
was luminous in the dark. The lights which are 
ibmetimes feen in burial grounds undoubtedly 
proceed from this caufe alone*.' Similar appear- 
^ces have been obiibrved s^ut the beds of flck 
perfons, probably in putrid difeafes: oneof thefe 
was obferved about the body and the bed of a lick 
woman at Milan>. which fled from the hand that ap- 
proached it, but was at length difperfed by a flream 
of air. It is well known that the fweat often contains 
a confiderable quantity of phofphoric matter f. 

Certain ftony matters are called phofphoric^ but 
do not in hiBt contain a particle of that fubftance. 
The moft remarkable ftone of this kind has been 
already noticed^ I mean the Bolognian ftme^ fb 
called fit>m the place where it is ufually found. 
MargraiTiays, that the Bolognian ftone is fbfc, fria- 
ble, heavy, cryftallized, and incapable of efffervefcing 
•with acids, till it has been calcined in contadb with 
&el, and with a free accefs of air. Thefe qualities 
have induced him toclafs it among the heavy fufible 
fpars, all of which are capable of being rendered 
phofphorefcent. After analyzing thefe fubftances, 
lie concludes, that they all contain vitriolic acid 
combined with calcareous earth, and that they are 
i^coxufe ieienites. In order to make thefe ftones 

T frifft. Oft, ^y6. tllad.s87. 


!t^6 Solar Fbo/pbcru '- [Book Vf. 

jrfiofphorcfccnt, they itiuft be heated red hot, and 
afterwards reduced to powder. This is to be made 
into a pafte with gummy matter, and to be cut into 
cakes as thin as a knife. After thefc cakes have 
been heated in' contact with charcoal, diey arc fit 
for ufe. What is called the phofphorus of Bald- 
win is a combination of clialk with nitrous acid; 
and the phofphorus of Homberg is a combination 
of quick lime with muriatic acid. All thcfe fub* 
•fiances have the property of ihining in the dark 
for fome minutes, after having been exposed to the 
light of the fun, or, according tg Margraff, after 
having been fimply heated. Moft fubftances, 
after having been held in a bright light, cniit fome 
faint light on being fuddcnly removed into a very 
dark place, but the light afforded by the fubflrances 
above defcribed is fo remarkable as to have at« 
traded particular attention. 

Bolognian ftone can be illuminated by the light 
of a candle, but not by the light of the moon, or 
of another phofphorus. When one part of it is 
illuminjited, it is not communicated to another. 
.Two ieconds will give it all the Jight it is capable 
of reccivii^, but one fecond will imperfectly illu- 
minate itr Some fpecimens will cbtitinue vifible 
for thirty minutes j but in general the light is not 
vivid for more than four minutes. - 

Father Bcccaria, having inclofed fome pieces of 
extraordinary good folar phofphorus in tubes^ 
into which the light was adm«t4(i ^through 
glafs, aflerts, that the phofphorus was of that co- 
lour only which it; imbibed: .All thefc phofphori 


Chap- 36-] PyropborL 487 

will lofe their virtue by being long expofed to 
open day* Some of them will prefcrvc their 
beauty a long time though plunged in water, which 
in the end, however, deftroys them; fomeofthcm 
will Ihine^ith peculiar fplendor, while diffolving in 
warm water, which is pardy to be attributed to the 
heat they imbibe in this procefs. 

The fubftances known by the name of pyro- 
phori, which fpontaneoufly t^ke fire when expofed 
to the air, are varioufly prepared, A pyropborm 
may be very eafily triade, by mixing alum or any 
vitriolic fait with charcoal, or any matter containing 
charcoal, and keeping them in a red heat for an 
hour, the air being excluded j this operarion may 
be performed in the bowl of a tobacco pipe. The 
pyrophori, when made, mud be very carefully kept 
from the air; for if the veflcl in which they arc con- 
tained Ihould be accidentally opened or broken, 
there is danger of their' fetting fire to any thing 
with which they come in contaft. 

The calcareous, or folar phofphori, and die pyro- 
phori, have two ftriking circumlJances in common, 
which are, that they are both prepared by the ap- 
plication of heat, and both lofe tteir properties by 
cxpofure to air; that their properties, therefore, 
proceed from the fame caufe, is extremely probable, 
and this caufe may probably be the attraftion of 
oxygen from the atmofpherc. It has been imagined, 
that the calcareous phofphori lofc their property by 
cxpofure to fight; but this is a miftake, for its 
properties remain uninjured by expofure to light iii 
clofed velTels. 


a«» Pjrophcrus. [BooKVIl 

It muft be confefled^ however, that the nature 
both of the calcareous phofphori^ and of the pyix>- 
phori, has never been fully explained. It is only 
neceflary in this place to caution the reader againft 
confounding them with phofphorus^ the proper fub- 
jeft of this chapter, from which they are eflfentially 

Dr. Prieffley put a quantity of pyrophorus into 
one of the fmall jars ufed for making experiment? 
upon air in quickfilver, dien filling up the vefl&l 
with that fluid, he inverted it in a bafon of the 
fame, and threw in dephlogifticated air at difiercnt 
times : it always occafioned a fodden and violent 
accenfion, like the flafiiing of gonpowder, and the 
ur was greatly diminiihed. 


Chap. 3^3 t a«9 1 

Chap. XXXVlh 


Ctiurai Properties of Sulphwr. — N^Oural Hiftory rf Sitlftur^iA 
Vniw wifb Barths.'ii^fVitb Aikalies.'^Uver rf Sufykmr.^4^ 
Artifidal/ulfhurious W^^s,^^lJ/es •f^dfbur. 

SULPHUR is another fimplc inflammable fub- 
ftance^ which agrees in fome properties widi 
jphoiphorus. Like that it melts with a gentle hca^ 
and is capable of a gradual as well as of a rapid 
combuftion^ in proportion to the degree of heat 
applied to it.. 

In treating of other bodies, particularly the me- 
tallic, feveral hive been mentioned with, which 
fulphur is found united in the bowels of the earth : 
few fubftances are indeed m6re abundant in nature 
than fulphur ; it alfo enters into the compofition of 
animal matters, and, in a very finall proportion, mto 
that of vcgctablesfc 

The fulphur of conimerce is extracted, by diftil- 
iadon, from the fubftance which has been fo cfften 
mentioned ilnder t;he name of pyrites, in which 
Itate it is Combined with iron j and is fo hard as to 
ftrike fire with ftecl. Pyrites in colour and ap-. 
pearance refcmblc brafs \ fome pieces are cubicali 
but in general this mineral has no determinate fonri. 
The fulphur obuihed by the firft diftilladdn is ftl- 
dom pure, from the fteams of other volatile fiib<* 

Vol. IL U fiances 

^90 Natural Uiftary of Sulphur. (Book VI, 

(lances which rife and arc condenfcd with it. It is 
purified by being melted in a ladle^ and kept in 
that flate till the impurities fettle at the. bottom. 
If it is an objefl to obtain fulphur of thegreateft 
purity^ tliis muil be effe&ed by fublimadon ; and 
in this ftate it is commonly fold under the name of 
flowers of brimftone. Even thefe, however, arc 
fomcrimes rendered impure by the fulphur taking 
fire; -which produces a mixture of vitrioFic acid. 
This is efFcftually removed by boiling the flowers 
in water, which diflbtvesthe aci^, and leaves the 
fulphur in a pure and mild ftate. 

Sulphur is fomecimes found, more or lefs pure, in 
the neighbourhood of volcanos, in which cafe it 
fecms to haVe been feparated, by fubcerraneous 
heat, from fome fubftance with which it was pre- 
vioufly combined. 

The method of burning fulphur for the prepa- 
ration of the vitriolic acid has already been defcrib- 
cd when q-eating of that acid. 

Sulphur has no aAion on filiceous earths, but 
very readily unites with the calcareous. It is alio 
capable of combination with magncfia, ponderous 
earth, and volatile alkali. It unioes, however, 
with much more violence with the fixed alkalies. 
.Aii thefe combinations are of a liver colour, and 
arc therefore called livers of fijlphur. By M. La- 
voificr they are much more properly denominated 
fulphurets of thefe fcveral fubftances, as fulphuret 
of lime, fulphuret of magnefia, &c. Thefe fub* 
ilances are fbluble in water, and have confiderable 
a&ion on a variety of other bodies. The combi>* 


Cliaf).37-T tJfei^of Sulphur. 291 

nations of fulphur with earths and alkalies' may be 
all decompofcd by means of acids, and the earthy 
fulphurets by means of the fixtd alkalies. Thefe 
fobftances, when diffolved in water, difengage a 
pecidiaf gas called hepatic gas. This gas is pr^« 
cifely the fame, from whatever kind of lulphuret it 
proceeds ; but none of them afford it unlcfb mixed 
with water* This gas, therefore, proceeds from a 
decompofition of water, and is found to confift of 
fulphur diflblved in inflammable air. When this 
gas comes in contav'^ with vital air it is decompofed^ 
the vital air and hydrogen uniting to form water, 
while the fulphur is precipitated in fmall flakes. 
This gas is, capable of folution in water, and by 
thefe means natural fulphureous waters may be' 
imitated. x 

The chief ufes to which fulphur is applied arc, "v 
the making of gunpowder and vitriolic acid. It is 
•Ifo ufed in bleaching, and is an article of fbme 
importance in the materia medica^ 

U % Crafw^ 

( «^ J [BookVL 

CftAP. xxxvm. 


Itaturtrfthe Carhonaceeut Prindpk.^^In *what Suhfiamc^s frinci* 
fallj founJ,'^CharcoaL^^Lamp'hlack,'^Strong AttraSUn of 
the Carbonaceous Prindpkfor Oxy^en.^-^Its V/e in thi KeJtUm, 
tien of MetatsJ'^Plumhago, or Black Leadj^-^Ilt ^wxrwits XJftM 
in fbr dirts. 

THE word carbon is adopted from dte m)nner»* 
clature of the French chemifts, to cx{)refe an 
irtfemmablc matter which conftttmes the chkf part 
of the weight of charcoal, pitcoal^ &c. and which, 
with different proportions of hydrogen^ or the liiafe 
of infiammable gas^ fornns the difl^rent kiflds of 

By the comfauftion of carbon a pecirfkr acid i» 
formed, which is fohible in, water, unitti whh iSlkst^ 
line bafes, and poffeffes all the properties of acids 
in general, though in a weak degree. This acid 
has already been treated of under the name of 
carbonic acid gas, or fixed ain 

Carbon exifts in great quanuties in fodils, as the 
greater number of calcareous ftones and earths are 
found united with it; k is alfo one of the con(ti- 
tuent parts of the atmofphere, in both which dates 
it is combined with oxygen. It is found united 
with earthy matter and oil in the extenfive ftrata of 
pit-coal^ and with iron in the matter which is 
called plumbagOj or black l^ad* Carbon alfo exifts 

in all vegetable and aniooal fubftances^ and confti* 
tucts a confiderable part of their weighty pamcular- 
ly of thofe vegetable matters which are the moi^ 
firm. The ftatc of grcatcft purity to which carbon 
can be reduced is, by burning wood in fuch a mao- 
jier as to reduce it to. charcoal^ which^ when wcU 
made, contains carbon united with only ^ very 
fmall proportion of fuch matter contained in vege- 
table fubftances as cannot be driven off with beat, 
fuch as earthy and faline matter^ with a very minute 
portion of iron. In order to convert wood intQ 
charcoal) the only circumftances neceflary ai:e the 
application of heat whik the air is exdudeci The 
only elementary fubftances wluch feem to be uni- 
vcrfal in the vegetable kingdom are, carbon, hydro* 
gen, and oxygen. The former of thefe fubftances 
has very little attra^ion for caloric, or the matter of 
lieat, and therefore cannot be driven off in vapour^ 
at leaft by the heat of ordinary fires i the two latter^ 
however, have a ftrong attraflion for that principle, 
and therefore eafily aflume a gaflegus ftate. In the 
«>rdlhary temperature of the atmofphere thebarboj^ 
hydrogen, and oxygen, which conftitute the woooy'' 
fibre, feem to exift in a ftate of triple combination; 
but this is not thecafe when the teinp^atpre is altered. 
According to Nf • Lavoifier, if a heat, not exceed* 
ing that of boiling water, is applied, one part of the 
hydrogen combines with oxygen, and forms wateo 
the reft of the hydrogen combines with a part of 
the carbon, and forms volatile oil, while the remain* 
<kr of the carbon remains fixed at the bottom of 
the veflel. If a re^ heat, however, ia applied, aq 
y 3 WWWr 

194 L^^ St^ [Book VI, 

water comes over, carboi^ hsiving a ftrongcF artrae- 
tion at that tetnperatiire for oxygen than hydrogen 
liasy and therefore carbonic acid is produced s and 
the hydrogen being left free from other combinations^ 
unites with caloric, arid comes over in the form ef 
hydrogen gas. In this high temperature no oil is 

The folidity of charcoal depends on that of the 
wood from which it is procured, and the care, with 
which the procefs is conduced. In general it pre- 
fcrvei the form of the vegetable, unlefs that waa 
very fucculent. Pure oils, from decompofition by 
heat, afibrd a coal in very fine particles, callod 

In whatever manner the volatile matters can be 
difpellcd from vegetable or animal fubftances with- 
out the admillion of vital air, which would con- 
Aime the carbon, charcoal is produced, wiiich con- 
tains no ingredient capable of inflammation except 
carbon, and therefore, with refpeft to that proce6^ 
may be confidered as carbon iti^lf. 
;g^ Charcoal, expofed to the greateft heat without 
^^he prcfcncc of vital air, remains unconfumed and 
unchanged. This fa£b has been denied by the 
advocates for the phlogiftic hypothefis, who maintain 
that the pureft charcoal, treated in this way, afibrds 
a quantity of inflammable gas. It is now, how- 
ever, I believe, commonly admitted, that if riie 
charcpal is firfl: accurately dried, no inflammable 
gas is ptoduced, and therefore that which has 
been obfervcd by other chemifls is to be attribute 
(cd^to. the prefence of a fmall quantity of wator, 
ijNrhich, in a high temperature, i? dccompofed 

■ ■ t? 

Chap. 38.] Ufe of Charcoal in reducing Metals. ^95 

by charcoal. Dn Pricftley has obferved, that char- 
coal has a ftrong difpofition to attraft humidity 
from the atmofphcre. He found that charcoal 
prepared v\ the evening, and kept till the nnorning, 
became fenfibly moift, and unfit for hice experi- 
ments. This remarkable attradtion for water is, 
perhaps, to be attributed to the alkaline falts ufually 
contained in charcoal. 

From the very ftrong attraction which the car- 
bonaceous principle has for oxygen, there is no fub- 
ftance that can be applied to feparate it from that 
matter* Carbon, on the contrary, is capable of 
dccompofing all the acids except the boracic, the 
fluoric, and the muriatic, the unknown bafes of 
which have a ftronger attraction for oxygen than 

/ Charcoal readily decompofes the phofphoric and 
fulphuric acids, the bafes of which burn at a lower 
temperature ; 4nd (hisfaft evinces, (hat the degree of 
heat at which thecombuftion ofa body begins does not 
accurately mark its degree of ^ttraftion for oxygen. 

From the ftrong affinity of the carbonaceous 
principle for oxygen, charcoal is the moft pqwcr-r 
fvX ftibftance which can be ufed in the reduftion of 
metals. Charcoal has alfo another advantage over 
other inflammable fubftances in thefe operations, 
which is, that it bear^ a great degree of heat with- 
out volatilization. 

According to the cxperiq^ents^of Lfivoifier, in the. 

combuftion of one pound of charcoal, two pounds, 

liine ounces, one drachm, ten grains of oxygen gas 

ar? abforbed, and three poynds nin? ounces one 

U 4 draphm 


i^ Black Lead. [Book VI., 

drachm ten grains of carbonic acid gas are 


The carbonaceous principle, or carbon, is one of 
the moft important fubftances in nature. It is one of 
riie neceffary conflicuent parts of animal fubftances^ 
and enters into the compofition of all alimentaiy 
matters, flour, fugar, mucilage, oil, &c. It is alio 
the chief ingredient in all kinds of fuel. 

Plumbago, or black lead, is found to conGfi: 
of carbon combined with about one-tenth of its 
weight of iron. It appears to be fcarcely inflam- 
mable, but may, however, be almoft entirely con-' 
fumed with the produfbion of caii>onic acid gas, 
by keeping it heated to a great degree, and agitata- 
ed fo as to expofe it thoroughly to the air. It may 
be alfo deflagrated widh a large proportion of nitre 
in a red heat. It is found in a feparate ftate in a 
variety of places j but the fpecies beft adapted for 
making pencils comes chiefly from Burrowdale, 
in Cumberland. For this purpofe it is cut into 
thin ^plates, the edge of whioh, being fitted into a 
groove in a femi-cyKnder of wood, is then (awed 
oflfi fo as to leave the cavity entirely filled. The 
black lead is retained in its place by the other half 
of the cylinder, which is glued on. The makera 
of fmall fhot polilh and blacken its furface by agi- 
tating or rolling it in a calk with powder of plum- 
bago. This mineral is likewife u^d in the manu« 
fe&ure of razor-ftraps. 


Chap. 39-1 [ a97 3 

Chap. XXXIX. 

P I T C O A L. 

Cannel toal^^Kilkenny Coal.'^Ba^ey Coat^^Ptat.^'^okg,^^ 
Coal Tar, ^^Natural Hiflory of Coal.'^^Obfer'vations relative /# 
the Deluge. 

PIT COAL is a fubftance of which there arc 
many varieties, the caufes of which have not 
been afcertained, as all the kinds afford very nearly 
the fame refulcs by chemical analyfis. The moft 
remarkable varieties are, 

1. Newcastle coal is of a black colour and 
fliining appearance, where it has been lately broken. 
This fubftance undergoes an imperfeft fuQon when 
heated, fo as to cohere or cake. It burns with a 
lively flame, and is nearly confumed in the fire. It 
does not break equally in all direftions, and is com- 
pofed of laminae. 

2. Culm coal. This contains a large propor- 
tion of argillaceous earth, fo that after being burned 
its bulk is fcarcely diminifhcd. It burns with a 
lively flame, but its appearance is more dull and 
earthy than that of the former. This kind of coal 
is found in Sweden, and in fome parts of England. 

3- Slate coal. .This has very much the appear- 
ance of fome of the common kinds of flate, but it 
Jburns very cafily, with a copious and bright flame. 
It confifts chieQy pf argillaceous earthy and feems t» 


dps Camel and KiUtmf Coal^ [Book VI. 

have only been penetrated with bituminous or coal/ 

4. Caknel coal is of a dull black colour^ 
breaks eafily in any direAion, and in its fraAure 
preicnts a faiooth conchoidal fur&ce, if broken 
tranfverfcly. It is nearly confumed in the fire, 
burns with a lively flame, but if fuddenly heated 
flics in pieces with confiderable violence. This in- 
convenience is faid to be removed by previoufly 
immerfing it in water for fome hours*. Cannel 
coal does not foil the fingers, and admits of i)eing 
turned into fnuflfboxes, inkftands, trinkets, &cc. . 

The wQrd lithopthra^c, ufcd by fome mineralo- 
gifts, properly denotes ftone coal, and fcems moft 
applicable to cannel coal, as this, from its duU and 
uniform fr^fturci has* mofl: refemblance to a ftony 

5. Kilkenny coaK This is perhaps the moft 
fr?e from earthy matter of all the different fpeciea 
pf coali the earth contained in it not exceeding jhe 
twentieth part of its weight. This coal burns with 
lefs flame and fmoke f, and more ilowly and in- 
tenfely than the cannel coal^ 

^ It is cadomary in Lanca(hire to fprtnkle (alt npon cannel 
coal» to prevent its flying ; but I cannot fpeak decifively as to 
Its effe£b, having never fecn the experiment accurately made. 
Pofibly the water contained in the fait may have fome influence 
in preventing the cracking of the coal. 

f mikenny» the town in Ireland where this coal is pro* 
dnced, is pleafantly fituated ; it is watered by a plear and beao* 
*tiful river« and produces alfo a black marble variegated with 
white fpots. The place has therefore been proverbially cha- 
ra^rized— " Fire without fmoke» air without fog, water 
mthoat mnd» and the ftreets paved with marble.^' 

ۥ Sut- 

Chap. 39,] Peat or VCurf., 999 

6. Sulphureous coal. All thofe kinds of coal 
Kf. called by this name, which 'are mixed with 
particles of a yellow and nietallic appearance^ and 
which arc in fii6l a fpecies of pyrites, In confequence 
of this admixture they emit^ when burned, a ful- 
phurtous fmeli^ and h\\ to pieces when expofed to 
the adion of air and moifture^ 

7. BpvEY coal, xylanthrax, is of a brown or 
browniih black colour, apd of a yellow laminar 
texture. The laminae are frequently flexible when 
frefh dug, though they generally harden on expofure ^ 
to air. It feems to confift of wood penetrated by 
petrol or bitumen^ and frequently contains pyrites, 
;^uai, and vierioL 

8. Peat or turf, geanthrajL. It may admit of 
doubt how far it is proper to confider peat among 
the fpecies of coal ; bpt s^s fome philofophers of 
great authority have at libutcd every kind of coal 
to a vegetable origin, and as fome kinds are deci^ 
fively fo, the rcafon of this arrangement will be 
obvious. Wbat is properly called peat is furmcd 
by the growth of a particular vegetable matter, 
peat mofs, which increafes to fuch a degree in 
.|noori(h grounds as to forfn (Irata of many (ttt 
in thickncfe- When peat is frcfh dug from belqw 
the fur face, it is of a vilcid confiftence, hut hardens 
by expofure to the ^ir. It is often mixed with 
pyiites and ftony matters, which arc fcparated 
from it while ibfr, in which (tate it is formed into 
oblong mapTes fijr fuel. When diflillcd, it affords 
^yafcr, oil, and volatile alkali, which are precifely 
f|ie products afforded by the diftillacion of pit* 

% coaU 

30O Lord DundcnalFs C^al Tar. [Book VI, 

coal. A kind of peat is Ibund near Newfewy, in 
Berkfhire, which contains but litlk eardi, and 
confifts of wood, branches, twigs, 'roots, wi(h 
leaves, graft, ftraw, and weeds. What is diig on 
moors, under the name of turf, frequently contsoiis 
« mixture of peat. 

Coal, when heated and inflamed to fiidi a He* 
gree as to expel the more volatile parts, forois a 
kind of mineral charcoal, called coke, which is 
highly uftful in the property of affording a ftrong, 
clear, and lafting fire, without forming a cohefive 
mafs, which would prove very prejudicial in ihc 
fmelting of metals. It is alfo ufcd in drying thdfe 
fubftances which would be injured by the Aide 
fmoke of common coal. 

Lord Dundonald was the firft perfon who im- 
proved this procefs, by collefting the tar and vc4a- 
tilr alkali, which arc driven off from the corf, 
while it is converted into coke. His mediod has 
been adopted with much advantage in feveral parts 
of Britain. The. coal is put into ovens, which dfc 
heated by fires lighted beneath, and the liquid mat- 
ter is forced through an iron pipe infetted into the 
top of the oven, arid which communicates with 
proper condenfing veffels. By this procefs a 
corrofive watery liquor and two forts of oil arc ob- 
tained. Six barrels of the mixed oily matter pro- 
duce about five barrels of oil of a thicker confif- 
tence; of the oil thus thickened, one part is lighter 
^an the othcij which is drawn off, and is not at 



Chap* 39.} Natural Hi/lmy flf Oaa/r jof 

prefent xipplied to any ufe*. The thicker part \s 
xtStd as an inferior .kind of tsar. 

Coalj Uhe moft other coctftdenMe mafles of 
nutter found near the furface of the carthj is diA 
pofed in beds or ftrata> which are fometkiies paraUd 
with the hori»on> but generally form ^ different 
aftglea with rcfpo& to it; the lame ftratum uniformly 
preferves the fame direftion. The ftrata of coal 
aft di4>ofed between ftrata of oth^r niatters. The 
following ftrata ai)c ufually found in thofe diftri6U 
of country, both in England and Scotland, wbeie 
coal abounds : whinftone, freeftone, fandftone 
«r freeftone of a coarfer tcsxture, metalftone, whidi^ 
is a hard argilkiceous fHibftaiKe, containing balls of 
iron ere and £hiver, which i$ the moft commoii of 
tfaenm ^U, and is- an indurated bole, ufualty of ^ 
Uacldfti colour. 

Tbefe ftrata do not bear on each other in the 
feme order in difierenc coHieries, nor are they of 
any unifbrm thicknefe. The ftrata of coal them^ 
ftlTca are divided by other partings, called l^a^h and 
M&rrx, into innumerable cubic, prifmatic, and 
shooikoidai figures. 

In all places where the ftrata lie regularly, they 
9K divided and fubdivided in the manner above 
iiientk)Ded, and (bmetimes exeend uninterruptedly 
dlorongfa a confiderable diftrid. This regularity, 
lowcver, is frequently broken by gaps filled by 
other noatter,. which has evidently fallen in, in 
MDfti{iience of th4 ftrata having been fepar^ted 

* Sec BUhof Watfoft's £%«♦ 

30$ Natural Htftttry of Coal.' [BookVl* 

from each other by fome violent conTulfioiu The 
Jargeft gaps are called dykes, and defeend from the 
jSirface of the earth, fbmetimes perpendicularly^ 
ibmetimes obliquely, to the greateft depths ever 
tried. On each fide of thefe gaps the ftrata corrc- 
ipondj but they are often funk fcveral feet or fe- 
thonns lower on one fide than the other, and this i» 
called a dip. 

With refptrft to the origin of pitcoal, it is the 
opinion of Dr. Black, Biliop Waclbn> and other 
phik>(bphers of high repuration, that the ftrata of 
coal were formerly Lrge colleaions of vcgii table 
matter at the futfece of the earth. In diftant ages, ^ 
Britain was probably almoft entirely covered with 
immenfe forefts apd coUedions of peat mofs, which 

. (according to the opinion of thefe naturalifts) being^ 
covered with quantities of fand or earth brought by 
floods, or by more gradual caufes, as the fallingof the 
fubftance of the neighbouring hills, has been prefied 
and confolklated, in courfe of time, into the fub- 
ftance called pit coal. The furfece of the earth has 
alfo been probably rendered unequal in a variety 
of places by the aftion of earthquakes; this would 
-give rife to the formation of lakes in thofe places 
which were depreflfed. In this manner, a quandty 
of vegetable matter would become covered by 
deppficion from water. Volcanic eruptions muft 

' often alfo have overwhelmed large collc6tions rf 
vegetable matters. Wc even find vegetable mat- 
ter in an intermediate ftate between organized 
▼egjctable fubftances and coal; for peat has ftill 
fomc ftaall remains of organic texture^ but feems 


Chap. 39.] Origin mid Analyfis of Pit-coal. joj^ 

chiefly to confifl of oily and inflammable maccer, 
which only requires time and the prcflure of fupc- 
incumbent firaca 10 convert it into the firm and 
compaft te:xture of coal.^ In fome places, the re- 
mains of forefts have been obferved conwrted into 
an imperfeft pit coal, in which the trunks, 
branches, bark, and roots of trees, arc difcernibk. 
In the neighbourhood of coal pits, impreflions of 
vegetable matters, and particularly of fern, are 
ufually obfervable. Now it is remarkable, that 
both peat mofs and fern are produced on wild and 
uncultivated lands, and this renders it ftill more 
probable, that coal in general owes its origin to 
peat mofs. Coal is found in thin and broad ftrata, 
fuch as might be expe£ted on thS fuppofition of its 
being derived from the decay of peat mofs, or col-, 
kdtions of other vegetables on the furfecc of the 
•earth. Coal is often covered with matter which 
cannot be fuppofed to have been created in it$_ 
prefent ftate, as fandftone, the particles of which 
are evidendy owing to the motion and friftion 
occafioned by water. It has been already men- 
tioned, that the produdts afforded by th^diftillation 
of peat gnofs and pit coal are precilely the (ame. 
We know of no fubftance purely and unqueftion- 
ably mineral, which afibrds produfts at all limilar, 
and it therefore on the whole feems probable, that 
the ftrata of coal found in difFerent countries, 
however extcnfive, owe their origin to vege&ble 
matter. The bituminous matters feem alfo to be 
exudations from vegetable matters buried in the 
cai-th. . 


jof Oripn ef PiteoJ. [BookVI< 

In confirmadon of the fame opinion^ I add die 
fcdlowing extraA from die kte ingenious Mr. 
"Wbitehurft's Inquiry into the original State of 
the Earth. ^ AU tne ftraca incumbent on coalj 
wh^er argillaceous ftone or clay, contain figured 
(tones, reprefendng a vaft variety of vegetables) or 
the impreflions of them/ as reeds of various kinds^ 
ftriated and jointed at different diftances> the 
euphorbia of the Eafi Indies, the American ferns, 
cqrfn^rafs, and many other ipccies of the vegetable 
kii^dorti. They are inclofed in the iblid fubftanca 
of the ftone, &c. Thefe vegetable Ibrms, and the 
ftrata containing them, are the certain indication of 
coal, not only in Dcrbyffaire, but in every part of th# 
kingdom which I'haveviiitedi and I am infornaed^ 
that the fame phenomenon bokb equally true in every 
other part of the world yet explored.' In general, 
the ftone which holds fofiil plants is either very 
hard and cloie, or bituminous, fb as to afibrd no 
accefs to water. 

The great difficulty in this hypothefis refults 
from the immenie quantities of thcie matters which 
art found b the earth, and this difficulty cah only 
be removed by rcfcrrii^ to a fiift> which is ftp- 
ported by the traditions of every nation tipOBeardit 
the univerfal deluge. 

Among mafiy other curioua obfisrvadom, rekdng 
to the deliige smd its remains^ made by Iit4 
Scheuchier and his^ brother^ the Dodor informs us 
cf the trunk of a tree, nine Paris feet in length, with 
feme part of its branches ftill left upoa it, which i» 
lodged upon the fummit of mount Stella, the chief 
$ of 

Ctiap. 39.^ Proofs of the Deluge. jb j 

. of all the Alps of Switzerland, which, a^rcording t6 
the barometer, is more than two Englifli ftatutc 
miles 'perpendicular in height, and four thoufand 
feet higher than any trees or vegetables are ol;»(erved 

. to grow J he concludes, therefore, that it was left 
there by the fubfidencc of the waters of the deluge. 
Another modern writer alfo very properly remarks, 
* When we find on any ftones an exaft refcmblance 
ti a plant, a ]eaf, or fomc fruit, that we are ac- 
quainted with. If thele leaves arc bent or folded, 
if they crofs each Other, or lie one upon another, 
they are certain indications that the plant or fruit (b 
reprefented is an impreffion made by a natural 
body*/ Specimens of thisdefcription are frequently 

Not only vegetables, hbwetrd^ but parts of ani- 
mals alfo, are met with, deeply plunged in the ftra- 
ta of the earth, for the prefcnce of which, in fuch 
fituatiohs, we-tiannot account, ejccept by fuppofing^ 
that they were depolited durihg the deliige, wheii 
hot ohly the windows of heaven wer^ opened, but 
the fountains of the great de^p wdre Brokeh lipi 
expreffions which denote, in the ftrong ftyle of ori- 
ental imagery, the extenfivehefi of that vaft dif* 
turbance of cohvulfion which happened to this 
globe. A folfil Ikelcton of an alligator, twelve 
61- fourteen feet in leiigth, Was difcovered in the 
tliff of ^n alum rock, near Whitby, in Yorklhirc. 
In a gravel pit of Suffolk, abounding with foflil 
ihells, the entire fteletoh of a whale Was dilcov^rcdj 

* Le {^Indie Spt ft. de la Nature, Dial. 25. 

Toi.II. X tha 

jo6 Proofs ^tie [Book VI. 

the bones of which, ^hen they became friabk by 
cxpofure to the air, were employed by a farmer for 
the manuring of his land. Fragments of an elephant's 
tooth were dug from a gravel pit at the end of 
Gray's Inn Lane, at the depth of twelve feet. 
From thefe and other fads it Teems probable at leaft, 
that this part of the world, before the flood, con- 
tained animals which now are very rarely found, or 
are totally incapable of exifting in fuch a climate. 
ThisconGdcration will lead us to conclude, that the 
deluge not only deftroyed th^ greater part of the 
animals then exifting, but produced a confiderable 
alteration in the conftitution of the globe, and a 
permanent revolution in fome of the laws of nature, 
of which the change that took place in the lengdi of 
hunnan life is one ftriking inftance. The earth, and 
almoft every part of it, is ftorcd with the remains of 
, trees, plant^ and fruits ; of fifli, teftaceoils, cruftacc- 
ous,and fquamous, and of other occafional inhabi- 
tants of the waters. The fpoils of land animals arc 
alfo met widi, but in much fmallcr quantities, which 
it is not difficult to account for, when we confider, 
that the waters of the fca occupy mbre than twice as 
much of the globe as the land, and that the waters 
are much more copioufly fupplied with animals of 
confiderable magnitude, than the land. Add to this, 
that the clafles of corallines, lithophuta> and many 
of the teftaceous kinds, are of a lubftance as hard as 
ftone, and of a much more durable texture j whence 
it is not to be accounted a matter of furprize that 
they abound fo much in the earth in the form of petri- 
faiftions. We are to rccoUeft alfo, that the cataf- 
.4 trophc 

Chap. 39;3 ' Univrr/id Dflugif. 307 

trophc of a deluge would foon corrupt, deftroy, 
and difperft the parts of fuch living creatures ^s die 
in the waters \ whUe the natives of the fca would 
ilruggle with the difficulties of an inundation, 
and be ar lafl depofited^ perhaps alive, in the car4i> 
when the fetdement of the ftrata took place, and 
the waters retreatedj^ as k i$ evident that many of 
tiiem adually were, from die poftures and circum* 
ftances in which they have been difcovercd*. 

^ See Jones's Phyfiological Difquifitions* 

X2 Chaf« 

't 2ot ] [BookVI, 

Chap. XL. 


Na/ttre oftif Preperiies rf' Napbta.^^^Burmng Fountaims, — /V/r»* 
' leum.'^Mineral Pitch, or Barhadots Tar.^^Lakt Afpbaltesj^^ 

J/phaltum \ honv colUSid^-^ElaJlic BUum€n*''^omp$MenLPrim' 

ciples of tbifi Sidfiances. 

ALL theft fubftanccs arc of the bkuminoos kind, 
and are, indeed, all of die faine nature, but 
differ in confiftence. Naphta 13 an oily fluids which^ 
in its greateft degree of purity, is nearly colourlefs, 
is extremely volatile wd fubtile, and fo light as to 
float even on fpirits of wine. It has a ftrong op- 
preffive fmell, .and evaporates fpontaneoufly^, 
Like other oils, it burns with fmoke. It is faid 
t6 be gathered at the futface of certain wcUs in 
Perfia, and is rarely found in Europe* 

The vapour of naphta, which iffues through th« 
crevices of the earth, is generally fuppofed-to be 
the caufe of the flame which is fometimes obferved 
on waters, fountains, &c. At Chittagdn, in the 
Eaft Indies, there is a fountain which burfl;& into 
flame of its own accord, whenever it has been ex- 
dnguifhed by accident i this fountam has its deity 
and its priefts; and fome Europeans, fufpefting the 
whole to be a pious fraud, pulled d<^n the wall, 
&c/ but found that the vapour adually kindled 
fpontaneoufly when put out* It is poflible^ how- 

Chap. 40.] PetrokufHr Ajphdium^ idc. joj^ 

ev:er, chat this flame may be fed bf inflammable air 
inftead of naphta. 

petroleum, which is of a thicker confiftehce, atid 
more weighty Aan naphta^ is much more common. 
It is of a yeilow or brown colour, and is found ih 
Switzerland, Sicily, Italy, and France./ It iflucs 
from the crevices of rocks, or is found floating on 
the forface of fprings* The different kinds of petro- 
lea, on diflillation, yield naphta, while a coaly refi<* 
duum remains in the retort. 

Barbadoes f;ar is of a thicker confiftence than 
{>ctroleum, and is alfo called mineral pitch ; it was 
formerly found near Babylon, and conftituted, acr 
cording td Vitruvius, when mixed with lime, the 
cement which was ufcd in building the walls of that 
city. It is at preftnt found in feveral parts of 
Europe and in Americst, where it drops, or diflils^ 
gradually from rocks, 

Afphaltum is a fubftance much refembling Bar* 
badoes tar ; it is alfo called Jews pitch, and is 
thrown up in a liquid form from the bottom of the 
lake where Sodom and Gomorrah anciently ftood. 
From the produftion of this fubftancc this was call- 
ed the Lake Afphaltes, from a Greek word denot-* 
ing bitumen. The bitumen floating on the furface 
of the water is hardened by the heat of the fun, ar.4 
is in thatftate colledlcd by the Arabs on thefhore, 
where it is thrown^ The eaflern afphaltum is fel- 
dom brought to Europe, but is ufed by the inha- 
bitants as pitch. * 

*A11 thefe thicker bitumens may be rendered 
thinner by diftlUation, and may be converted into 

X 3 zxi 

^ta El^icBitunm. [BookVt 

9^o&f fluid, the tdnqitjf of whichis inaresTedby 
the repetition of the procefs ; at every diftilktton z 
Quantity of charcoal,, earthy nf atter, and catbonic 
acid g^5 being feparatcsd from then). 

In Oh/ervatumsjur la PbgfiqtUi for Januaryt 1788, 
vol. xxxii. M. de la^letherie makes ncicntbn of a 
mineral elaftic bitumen analogous to the caout^ 
chouo, or elaftic gum^ and which is found in 

The production of all tfaefe bitumens is attribute 
ed to the aftion of fubterraneoiis fire on ftrata of 
ptt€otili by which the oily parts are feparatcd and 
iublimcd ift the fame maniier as by artificial beat. 

Biihop Watfon mendons a cUriou3 experiment, 
which illuftrates the relation of thefe four bitumens 
tp each odien The moft tranl|>aren( oil of turpen* 
tine^ reiembling napht^^ n>ay be changed into an 
oil refcmbling petroleum, by mixing ik With a fmall 
portion of vitriolic acid j with a larger proportion 
of the acid the mixture becomes black and tena* 
cious like Barbadoes tar, and the proportions of 
the ingredients may be io adjufted, that the mixture 
will even acquire a folid confiftence like afpha^^ 


Ch)sp.4iO £ 3" ] 

Chap. XLI. 

jet, amber, ambergris, an0 
mineral tallow, 

Ge/ural Prepertin of Jit.^-^Its Naiun and OrigiM.^^mJmlir.'^ 
Aad pf Amhir.'-^Natmral Hiftory rf Ankff.^^l^igkrmt Ofi* 
uiotts of its Origin^^'^Amhirgru.^^Ifs Kuiwrdd Siffi^rj^^^ 
Miner al Tallow. 

JET is a very compa6): bitumen, harder than al- 
phaltum, always black, and fufceptible of a good 
polifh. It is fo light as to fwim on water, becomes 
eledrical when rubbed^ and is called black amber. 
When burned it emits a bituminous fmcU. Jjpt 
feems nearly allied to coal, and particularly to that 
ipecies which is called cannel coal^ it is diftinguilhed 
chiefly by its ftrufture, being compofed of fibres 
parallel to each other like thofe of wood. It feentf 
in fa£t to be wood^ which has been long buried i;i 
the earth, and penetrated by mineral fteam, fo as to 
aflume the appearance and Iblidity of coaL 

Amber is the fubftance known to the ancients 
under the name of eleftrum and fuccinum. In this 
fubftance the property, which certain bodies have, 
of attrafting light fubftances, when rubbed, was firft 
obferved, and was therefore called cleftricity. The 
moft valuable amber is perfectly tranfparent, of a 
pale yellow, and is much more efteemed when it 
happens to contain any extraneous fubftance, fuch 
as leayes> infeAs, &c. When broken it prefents a 

X 4 polilhcd 

3 1 « Amhar. [Book VH 

poHQied furface at the place of/the frafturc. Am- 
ber docs not readily diffolve in any fluid we are yet 
acquainted with. Spirit of wine has fome fiiiall 
cffeft upon it, and from this combination a tinftui^ 
is produced, but the quantity it diflblves is very 
fmall. When applied to the flame of a candle it 
readily takes fire, and burns with a Jbright white 
flame and thick fmoke, and leaves a confiderable 
quantity of charcoal. Amber expofed to heat, 

• without the adtion of flame, foftens and fwelh very 
confiderably. Difl:illed in a retort by a heat gra-. 
dually raifed, it affords a watery fluid cf a red co- 
*laur, manifeftly acid j this acid Ipiric retains the 
ftrong fmell of amber; an acid volatile fait after- 
wards pafles over, which cryflallizes * in* fmall 
white or yellowifh needles in the neck of the retort. 
This fait is fucceeded by a white and light oil much 
refenibling naphtaj By continuance of the pro- 
cefs, and in proportion as the heat is increafed, the 
oily^niatter which comes over is coloured and more 
vifcid, like petroleum. What remains at the bot- 
tom of the retort is a blacjc mafs refembling afphal- 
tum. * It appears, therefore, from diftillation, that 
the analogy of amber with th^ other bitumens is 
very ftrong. 

A. gende heat is fufficient to raife the concrete 

^ volatile fait of amber, and care muft be taken to 
regulate it fo as not to force up the oil, when it is re- 
quired to have the fait in a fcparate ftate. This faline 
matter was for lome time fuppofed to bean alkaline 

' <alr, but ha^ been fince found to be an acid of peculiv 


Chap. 41.] Natural ISJcry nf Amber. 313 

properties^ and capable of combinadoq with dka« 
lies^ earths^ and metallic calces. 

Amber is ufually dug out x)f the earth, and a- 
bounds particularly in the Pruflian dominions* Wood 
is ufually found near it, and it is therefore believed 
to be of vegetable origin. Its analyfis feems to (heiv, 
that it confifts of an oil rendered concrete by com* 
bination with an acid. The moft tranfparent (ped- 
mens are ufually found on the fea-{hore, particukrly 
on the (hores of the Baltic, in Ducal Pruflia, Am- 
ber is not always of a yellow colour; it is fbmc-^ 
times brown, fometimes quite opake, and fomc- 
times black. Some have fuppofed that it is entirely 
of mineral origin, but thi$ is difproved by its; difHl-* 
Jation,and by the foreign bodies which are frequent* 
ly contained in it, and which fecm to dcmonftratc 
that it was once in a Quid ftate. 

HofFmaa and Newman fay, that it is found upon 
the fta-fliore, or- upon the furface of waters, 
particularly after. great ftorms, when it is collefted 
*by means of nets i but that the . greater part of iti$ 
dug out of pitsl The firft ilratum is land, then 
clay, then a layer of branches and trunks of tree% 
then a confiderable quantity of pyrites, whence vi- 
triol is prepared; and laftly, a bed of fand, through 
which the amber is difperfed in fmall pieces, or col- 
ledted together in heaps. This account gready 6- 
vours the idea of the vegetable origin of amber j 
but Wallerius aflcrts^ that the blaqk and dark co- 
loured amber is often found in the bowels of ceta- 
ceous fiihes. M. Girtanner has a peculiar opinion 
pn this fubjeft j he thinks that amber is a vegetable 


514 Jmhergris. [BookVL 

, oil rendered concrete hj the acid of ants ; it is 
that kind of ants called formica rufa by Linnasm, 
which prepares it, according to this author. Thefc 
infers dwell in old forefts of fir trees, where the 
foffil amber is found, which, when firft dug, is duc- 
tile like way, and becomes hard on expofure to air. 
No iniefk is fo commonly found in amber as the 

Ambergris is of much the fame nature as amber, 
but differs from it by its particular confiftence, which 
nearly approaches to that of bees wax. Its ftruc- 
ture is foraetimes like bees wax, but fbmetimes it 
is granulated, and Appears opake, or of a dark grqr- 
Experiments prove that it refembles amber in its 
nature. When analyzed it is found to confift of 
phlegm> a volatile acid pardy fluid, oil, and a little 
coaly matter. It diflTolves more readily in fpirit of 
Wine than amber. 

It is moft common in the Indian feas, on the 
eaftem coaft of Africa, Madagafcar, &c. and is found 
cither floating on the fea, or caft on the fea-fhore- 
In this fubftance animal and Vegetable remains are 
fometimes found, as for inftancc, parts of birds, &c. 

The origin of this fubftance is probably the lame 
with that of amber. According to M. Aublet (in 
his Hiftqire de la Guiane) it is nothing more than the 
juice of a tree infpiflatcd by evaporation; and if this 
is true, it is a fubftance which belongs properly 
to the vegetable kingdom. . The tree which is faid 
to produce it grows in Guiana, and is called cuma^ 
but has not been examined by other botanifts. 
When a branch is broken by high winds, a largic 


Chap* 41.} lufuppojei Origin. 3 1 5 

<juantit7 of the juice exudes ; and if- it chances to 
have time to dry^ various maflb (fome of which 
have been fo large as to weigh one thoufand two 
hundred pounds and more) ai e carried into the rivers 
by heavy rains> and through them inco the iea> after« 
wards they are either thrown on the fhore or eaten 
by fome fifh, chiefly the fpermaceti whale> known 
by the name of pbyfiter-nuicrncephalus among kh- 
thyologifts. This kind of whale is extremely vora- 
cious of this gum-refinj and fwallows fuch large 
quantities when it meets with it» that it generally 
becomes (ick^ fo that thofe. emj^oyed in the 
fiihery of thcfe whales always expert to find fome 
amber mixed with the excrements and remains 
of other food in the bowels of thofe whales 
which are lean. Various authors> among whom is 
Father Santes, in his Ethiopia Orientalis^ who travel- 
led to various places on the African coa(V, and 
Bomare, fay, that fome fpecies of birds are alfo fond 
of eadng this fubflance, as well as whales and other 
fifhes. This accounts very well for the claws, beaks, 
bones, and feathers of birds, parts of vegetables, fhells, 
and bones of fifh^ and particularly for the beaks of 
the cutde-filhi Jepia oSlopediay which are fometimes 
'found in the mafs of this fubftance. M. Aublet 
brought fpccimens of this gum-refin, which he col- 
lected on the fpot, from the cuma tree at Guiana. 
It is of awhitifh brown colour, with a fhade of yel- 
low, and melts and bums like wax on the fire. M. 
Rouelle examined very carefully this fubftance, 
brought over by M. Aublet, and found that it pro- - 
duced exadtly the fame refults as good amber. 


'316 Mineral Talkw. [Book VI, 

Thcfe obfervations fccm to pkcc it beyond a 
doubt, that both amber and ambergris are vegetable 
produfby and th^t thofc who, from having found 
theft fubftances in the inteftines of whales, conclud- 
ed that it was a faecal mattei' of thofe animals, were 

Mineral tallow is a very peculiar fubftance. It was 
finind on the coafts of Finland, in^thc year 1736. 
Its fpecific gravity is 0.770, whereas that of tal- 
low is 0*969. It burns with a blue flame.and a fmc]l 
of greafe> leaving a black vifcid matter, which is 
mor^ difficultly confunned. It is found in ibme 
rocky parts of Perfia, but feems mixed with pctro- 
]eum. Dr. Herman, of Strafburgh, mentions a 
jpring, in the neighbourhood of that city, which 
'coQuins a fubflance of that nature difFufed through 
it, which fcparates on ebullition, ^nd may then be 
cx>Ile6ted. The origin of this fubftance is ua« 



Chap. 42.] ^ ' [ 317 1 

Chap- XLII. 

of the diamond, c ons'-idered, as 
an inflammable substance. 

Mxperiments proving the inflammahU Nature of the Diamond,'^ 
Experiments of M- Cadet. — Of D'Jrcet.^FitalJir uecej/ary 
to the Comhufiion of the Diamond.'^Experiments of Lavoi/ur*"^ 
Fiirther Experiments. '^Conclujson from the mfbole, 

THE external appearance of this peculiar and 
beautiful fubftancc has been already dcfcri- 
bed> but it is proper alfo to confider it in another 
point of view, as from fomc extraordinary experi- 
ments many naturalifts are difpofed to include it in 
the clafs of inflammables. 

It has long been underftood that diamonds, cx- 
pofed to a high degree of heat, entirely difappear at 
the inftant that an appearance of combuftion is ob-i. 
ferved. 'M. Cadet expofed diamonds in covered 
and luted * crucibles to the violent heat of a forge 
during two hours, by which the diamonds only 
loft one fixteenth part of their weight: he is of 
opinion, that the confumption of diamonds in open 
vcffels is not a true volatilization, but merely an 
exfoliation occafioned by the expanfion of the air 
contained between the laminae of the diamond^ 

* Luting u a kind of earthy cement ufed by chemifb, and 
fiirmed in different ways. . , . 

5 .by 

3i8 Ccmbuftim 0f Diammds. [BookVL 

by which it is broken into portions fo minute as to 
cfcapc obfervation. M. D'Arcet oppofes to the 
above explanation, the efcape of the fubftance of 
the diamonds through the moft folid porcelain cru- 
cibles, and the luminous appearance noticed by 
Macqucr, and which was afterwards obfervcd by 
M. Roux to be an a£bual flame. It has, indeed, 
even been found, that diamonds incloled in a 
ball of porcelain earth, and expofed to heat, have 
been totally confumed; the fpace which the 
diamond occupied was found empty; no traces 
of it could be difcovcred, and yet the ball of por- 
celain, which was hardened by the heat, was appa- 
rently entire^ This experiment, according to Four- 
croy, has been frequently repeated with the fame 
extraordinary refult. It is found, however, that if 
the diamond is embedded in charcoal, and carefully 
inclofed infeveral crucibles placed within each other, 
and the whole covered with cement, it does not 
difappear from expofure to a very violent heatj it 
is only rendered black at its furface, and when this 
cruft is taken off, it appears in its original fplendor. 
It is therefore concluded, that perfcft exclufion from 
vital air is fufBcient to prevent the confumption of 
the diamond, as weH as of all other inflammable 
fubfl:ances; and it is therefore necefTary to fuppofc, 
that the porcelain earth, in which other diamonds 
were inclofed, fufFered fome fmall feparation from 
expofure to heat;, which, though fo minute as to 
efcape obfcrvarion after the ball was cold, were yet 
fuJ£cieot to admit the air. TJiis opinion has b^en 
fully confirmed by fome experiments of M. LavcM- 


Chap* 41.] Exferimenis m Diamonds. 319 

licr, who found, that diamonds arc only con- 
lumcd in proportion to the quantity of vital air to 
v^hich they arc cxpofcd. He alfo found, that the 
combuftion' of the diamond was attended with the 
formation of carbonic acid gas. This difcovcry 
may probably throw as much light on the nature 
of the diamond, as his other difcoreries have dif- 
fuied through almoft the whole extent of natural 
fcience. Some curious experiments on the dia- 
mond arc alfo detailed in the Annales de Chimic 
for November 1791. A piece of iron wire was 
fattened to the diamond intended to be burned, the 
iron was heated red hot, and in that ftate plunged 
into ajar of vital air; the iron rook fire, and com- 
municated the inflammation to the diamond, which 
burned in a moft vivid manner, and with uncom- 
nK>n braghtne(s« The Brazil diamonds, however, 
it is neceiTary to remark, could not be made to burn 
in this way. On the whole^ there can be no doubt 
that the diamond is truly an inflanunable fiibftance ; 
but a repetition of thefc cxpenBvc experiments is 
neceflary, in order accuracely to afcertain its nature, 
and to reconcile fome differences in the refults of 
iuch experiments as have been ah-eady made* 


' C S2<> 3 CBookVf. 

Chap. XLIII. 
the structure of the earth. 

yjc Curiofij of Man «r this Topic limited hjibe tFeaknifi •/ Iks 
Powers, — TbeBeify of the Earth dijpofedin Strata. — Decii^ities ef 
Mountains — DiJ^ofilion arid Order of the Strata. — Caldy IJUmd. 
^^Wbere Metals are u^udly found, — Probable State of the Eartlr 
at its Qreaiion^'^Lanuf by *whicb jilt erat ions 'would be produced, 
'^Foffil Shells, lie, accounted for ."^Formation of IfUauU^ 
\Sc.^Otber Irregularities of tbt Eartb^s Surface explmncd. 

AFTER the preceding furvcy of the natural 
contents of this globe of carthj and of their 
confiponent principles, the next objeft of attention 
is the earth itfclf, and the general arrangement of 
thofe fubftances of which it is compofed. Thefc 
are neither difpofed in a regular feries, according to 
their fpecific gravities^ nor yet thrown together in 
total diforder, as if by accident or chance. Human 
induftry has hitherto been able to penetrate but a 
very little way into the bowels of the earth, and wc 
can but know little of its interior parts. The 
depth of the earth, from the farface to the center, 
is more than four thoufand miles, and yet the deep* 
eft mine in Europe, that at Cotteberg, in Hungary, 
is not more than one thoufand yards deep ; ^\ the 
greatcft depth, therefore," fays an excellent writer, 
" to which avarice has ever jret penetrated, may be 
compared to the ptindure made in tHe body of ail 
elephant by the probofcis of a gnat/' 


th^. 43.J Earth eonfi^s'tf Strata. jii 

From if^hat h«i been difcovcrtdi however, of 
thpfe parts which ibe tnoft contiguoM to otir obfer^ 
Vadon^ hatundifts have compsif ed the ftruAure of 
the earth, to the icares of a book> or the coats of 
an onion. Except, hidei*d, in fonte of thofe ihi<« 
hicnfe mountains, which haVc.exiftcd froili the crea- 
tibn, of at Icaft from the dcWge^ where the mat- 
ter, from Whitevcr caufe, is morte faomogeneousi 
the earth is found to ronfift of various &*ata, or 
]ayers> which diBer according to the circumftanceft 
uf dimate and ficuacioni., Ti» furface^ in general^ 
evidently confifts of a cooifufed mixture of decayed 
animal and vegetable fubftanCes atid earths ruddy 
united together ; but wheh wis have penetrated 
)>clow the furfa<;e, we find the materials of the giobs 
arranged in a more regular rt)anntr» Somedm^j in-^ 
deedi we find helps of ftone, which do not confift of 
laycrs> but are confufed maffes of unequal thickncfs^ 
tod are dalled rocksi .The ftrata are, in genera^ 
extended through a whole coumrjf and, |icrhaps^ 
InritH fome interruptbm and Varieties^ through the 
globe itielfi Thefe extetrfive bodies ai'e finind moft 
regular when the country is flat, beings in diat cafe, 
nearly patallel to the homon^ iHough frequehdy dip<^ 
{>ing downwards in a certain angle 3 in many placet 
the bedi have a wave, as where the country conlifta 
of gendy waving hills and vales 1 here too they ge^^ 
heraUy dip. In travellthg a mile we, perhaps, paft 
through grpiind compo&d nidftl^of fimd, in am>^ 
ther mile we find it, perhaps, compofed of day ; 
and this is occafioned by the edges .of the different 
ftrata lying with an Obliquity to the horiaon. ' By 

VQfc.II. T the 

3t2 Inequalities ofEartVs Surface. [Book VI. 

the fame kind of proje6tion mountains, or ridges of 
mountains^ are produced^' which'^ in ^aeraij haire 
what is caDed a back and aface, the fonner fmoother 
and ths latter more rugged. We generally find toO| 
^n orie fide of a mountain, a more gradual alcent 
than on the other, which is occafioned by the ftrata^ 
which have rifen above the general level of the 
ftountry being abruptly broken off. Mountains 
are in general more abrupt towards the weft, and 
have a. more gentle declivity towards the eaft^ 
iience the weftern ccaft of countries is almoft al* 
ways fteeper than the eaftern. The back of a moun- 
tain ihews the obliquity wkh which the fhata fink 
into the ground $ the abrupt edge of the ftrata be- 
comes more floping, as timie, producing a gradual 
decay, draws the rubbifti fi-om above. Where the 
face of a country is fo irregular, its appearance de- 
pends on the different hardnefs or foftnefs of the 
ftrata. The abrupt rocks, which we obferve in 
many parts, ftem to have been compofed of an ad« 
vendtious mixture of different ftrata, which have 
refifled the injuries of time with unequal force. 
. Between the ftrata,^ layers of different clays are 
interpofed, which are called by the miners way« 
boards I they are feldom more than four or five^ and 
in fome inftances not more than one foot thick; 
they ferve. to mark and diftinguifli the different 
ftratai for in fiift the ftrata are themfolves com- 
pofed of different laminas *. 

♦ Whttcfiurfti- Chap. XVL 


Ghap. 4^.] Fiffiifes. 3ft j 

Every part of a ftratum may be confidered a« 
equally thick when covered with an incumbent bedj 
but when expofed to the adlion of the air, and other 
external agents, a great part of it, whether grit, lime* 
ftone, or toad-ftone, is decompofed and converted 
into earth or mould. Immediately under the foil 
the fragments of ftone are fmall, and gradually in- 
Tcrcafe to the. depth of fifteen or twenty feet, wherr 
it commonly appears folid, and fit for the inafon. 
Strata are ufually interrupted by clefts or fififures at 
difierent diilances, which feem to have been the 
cfFeds of violence. In theie fiflures only the ores 
of metals are to be found.. 

It has boen remarked, that we cannot, by digging 
into the earth, obtain a view of the pofidon and 
nature of the ftrata for more than fome. few hun- 
dreds of yards. There is, however, one curious 
inftance of an ifland, near the coaft of Pembroke* 
Ihirc, called Caldy Ifland> where the earth fujfereci 
the adion of fo unufual a difruption, that the ftrata, 
of which the whole ifland is comp^fed, are placed in 
a vertical position, fo that their edges are all expoied 
to view, and they may be obferved in fuccefllon 
from one end of the ifland to the othen Here then 
we have the Angular opportunity of obferving in 
what order they were originally placed, to the depth 
of two miles. At one end of the ifland they are 
not more than a foot thick> but increafe^ as we pro«>. 
cced, till they terminate in a ftratum ^ of red ftone, 
more than a mile in thicknefs, which,' with good 
reafon, is fuppofed to have been the loweft of then) 
all before they were elevated and thrown upon tl(eir 
Y 2 edges. 

3^4 Strata of the Earth. [Book VI. 

edges. The thinner ftrata, which were originally 
uppermoft, have foffil (hells and corallines in them; 
but I have not heard that any thing like the traces of 
lava are to be found to countenance the fuppolition^ 
that this Angular accident was occafioned by the 
explofive force of a volcano. 

The order of the ftrata in Derbyfhire is as follows: 
I. Millftohe-grit, a coarfe fand-ftone compofrd of 
granulated quartz and quartz pebbles. i. Shale or 
ftiver, or black laminated clay, much indurated. 

5. Lime-ftone, in various laminae. 4. Toad-ftone, a 
black' porous fubftance, hard, refemblingfcoria5,and 
apparently a volcanic produftion. 5. Lime-ftone. 

6. Toad-ftone. 7. Lime-ftone. 8. Toad-ftonc. 
9., Lime-ftone again. Such (the toad-ftone except- 
ed) appears to be the general order \i\ which the 
ftrata appear through the different regions of the 
earth, or at Icaft wherever the lime-ftone predomi- 
nates, which is in a confiderable proportion, though 
ift muft be remarked that the largeft mountains arc 
chiefty granite. Wherever, therefore, the firft of 
thefe ftrata appears on the furface, the fecond lies 
certainly under it, the third under the fecond, &c. 
ftjll excepting the toad-ftone, which, being a volca- 
nic produftion, may be fuppofed to be m fome 
meafure cafually in terpofcd. 

The toad-ftone interfefts all did mineral veins, and 
cuts oflF all communication between the upper and 
lower parts of the fifliires, being continued horizon- 
tally in one oninterruptcd mafs'.' Toad-ftonc is of an 
extremely hard and cldfe texture, fo much fo as even 
to prevent water from filtering tlirough it, at leaft in 


Chap. 43'] IVbere Ons are chiefy found. 345 

any quantity. It is pcrfedlly fimtlar to Iceland lava 
in appearance, and in being unafTaiiable by acids. 
Ic has no fifiures,* and frequently fills up the fifTures 
of the other ftrata ; in fine, it being not univerfal, 
but only an occafional appearance, there is the ut- 
moft probability that it is a fpecies of lava. It being 
inferted between the other flratafcems alfo to afford 
a proof, that it originally flowed from a volcano, 
the funnel or fhaft of which did not approach 
the open air, but difcharged its fiery contents be- 
tween the ftrata in all directions. When the toad- 
ftone is dug through, however, and the vein or 
fUTure purfued, the miner is never difappo>nted in 
meeting it again, as foon as he arrives at the ftra- 
turn of lime-ftone *. 

The ftrata of coal, argillaceous ftones, clay, &c. 
arc always incumbent on the ftrata of grit,^ fhale, 
and lime-ftone. The former are feldom in ftrata of 
above twenty feet thick, and generally not more 
than four or five ; the latter are in ftrata of from 
fifty to one hundred and fifty feet in thicknefs, or 
j^lepth t- 

All beds of gravel are fuppofed to have been de- 
pofited either by rivers or by the aftion of the itd^ 
apd the ftones that compoie them to have been 
rounded by attrition. It is no inconfiderable proof 
in favour of fuch a conjefture, that fea fhells, fltf . 
are fo frequently found with gravel. 

The argillaceous ftrata are only productive of 
iron and coal. The ores of copper, lead, zinc, &c. 

• Whitchurfl, Chap. XVL f !*>• 

Y 3 arc 

3i6 Order of Strata. [BookVL 

urc confined entirely to the lime-ftone ftrata, a few 
inftances excepted, where they are found in ihale. 

The difpofition of the fiiperficial ftrata, however^ 
differs, in mountainous and champaign countries. 
•.In a well which was dug at Amfterdam, to the 
depth of two hundred and thirty feet, the following 
fubftanccs were found in fucceffion * : fcven feet 
of vegetable earth, nine of turf, nine of foft clay, 
eight of fand, four of earth, t?n of clay, four of 
earth, ten of fand, two of clay, four bf white fand, 
one of foft earth, fourteen of fand, eight of clay 
mixed with fand, four of fca-fand mixed with fliells, 
then an hundred and two feet of foft clay, and then 
thirty-one feet of fand. 

* In a well dug at Marly, to the depth of an 
hundred feet, M. BufFon gives us a ftill more exaft 
enumeration of its layers of earth. Thirteen feet of 
a reddifli gravel, two of gravel mingled with a vitri- 
fiablc land, three of mud or (lime, two of marie, 
four of marly ftone, five of marie in duft mixed 
with vitrifiable fand, fix of very fine vitrifiablo 
fand, three of earthy marie, three of hard marie, 
one of gravel, one of eglantine, a ftone of the 
hardncfs and grain of marble, one of gravelly 
marie, one of .ftony marie, one of a coarfer kind 
of ftony marie, two of a coarfer kind ftill, one of 
vitrifiable fand mixed with foffil fliells, two of fine 
gravel, three of ftony marie, one of coarfe powder- 
ed marie, one of ftone, calcinable like marble^ 
three of grey fand, two of white fand, one of red 
fand ftreaked with whitc^ eight of grey fand with 

* Varenias, asquotc<} by M.Buffon, p. 358. 


Chap. 43.] Trying of Strata. 317 

ftcHs, threp of very fine fend, three of a fc«"d grey 
ftone, four of red fand ftreaked with white, three 
of white fand,, and fifteen of reddifh vitrifiable 

The dif€<5tion too in which the ftrata are found 
b alio exceedingly different in different fituations^ 
• When the continuity,', lays Mr- Jones, * of the ftrata 
is interrupted by a fi^adure, the fbrata are thrown 
out of that horizcxital pofition which is natural to 
them, and make an angle with the horizon; which 
mdSf be called the angle of their elevation or de* 
preffion ; the miners call it their dip. In this paie^ 
if the fucceifion of ilrata is accurately noted on one 
fide of the frafture, where a vein of coal or metal 
is found amongft them, it may thence be learned 
where the fame vein will, occur again on the other 
fide of the fra£ture; becaufe it will be found adja- 
cent to the fame ftrata as before. When the edges 
of the ftrata, on each fide a fiflfure, are thus parted 
and mifmatched, they are faid to trapi and the 
{pace between them is fiUed up with rubble, or 
ftones, or minerab, &c. Sometimes thefe fifliires 
arc the richeft parts of the foil, containing fuch 
matters as are not to be found elfewhere *• In 

* Some of the filTures in Cornwall are near twenty feet 
over, and commonly full, or near it, of metallic ao4 mineral 
matter. The fiiTures at the greateft depth are generally lai;geft: 
as we afcend they become gradually lefs, but more fri^q^ent 
and numerous : infomnch that if the globe was divided in tjyvo, 
and the ftrata viewed upon the face of the {edioi>i theigures 
would appear after the manner of a tree : at the bottom a large 
frunka which higher up is divided into branches, which break 

y + intu 

3i« Ordsr Qf the Siraia. [Book VI* 

fig. r. phte I. F* reprefcnts the fiffure, by which 
the ftrata are parted, and which is filled up with 
extraneous rubhifh*. carried ia al^r the ftrat^ 
were parted. The black veio of coal on 
the left fide, is fouad with five other ftrata 
^ I hut being interrupted by the fiffure F. 
where it cmei ou^ U^ the day^ the ftratum of (and. 
No. 4^ OB the right fide^ on account of the trapping, 
is found oppofitc to it : thence k is to be oolle&ed^ 
that thet fourth ftratum below that fand wiU be coal 5 
and when the angle of the diy i^ obfcrved^ it may 
be known where to fink a pit, and where the coal wiQ 
again appear to the day; provided the figure of the 
furface of the ground will permit it to fhcw itfelC 
When I was once at the bottom of a lead mine in 
Dertyihire, ^ miner informed roe, that the veins 
of the metal always make a greater ^^k wich the 
horizon than the fides of the mountaiado, in which 
they are found and come out to the day \ which wa^ 
probably occafioned by the ddcent of the waters 
of the flood, tearing away much of the matter 
from the fummit, and lodging it upon the fides and 
in the vallies beneadi^ after the ftrata had receive^ 
their inclination,' 

into lefler, and at the top into twigs. But the branches arc 
not continued in a ftrait line : they ftart afrefh, at fome little 
diftance on one fide, as in fig. 2. that by an intervening 
boundary ^the metaHic matter might be detained in its de- 
scent, and prevented from fmking away to the bottom of the 
earth. See Mr. Hutchinfon's Obfcrvations in the year 1706, 
PO16, 317. 




f hap. 43.5 Central Fire in the Earth. 3^9 

With refpeft to the more internal part^ of th? 
(carthj for the reafons aflTigned in the beginning of 
this chapter, nothing, can bckJvanced with certainty, 
^nd hypocheies cannot be relied on. 

By fome it has been luppofcd, that the center of 
the earth confifts of fire. Mn Kirwan, however, 
has fatisfadorily proved, that tfie notion of a cen- 
tral fire or heat is void of foundation. Since no 
authentic obfervatiqn affures us, that this heat in- 
/:reaies in proportion as we penetrate below the fur- 
iace of the earth i on the contrary, many experi- 
ments fcrvc to evince, that it rather decreafes 
{though never to lefs than thjrty-fix degrees) and 
that its variation at the fame diftance below the fur- 
face conftantly bears a proportion with the variatioq 
of the folar heat at the furiface<i 

The more general opinion is, that the ftrata ori- 
ginally lay horizontally, and were formed by a depo- 
(ition from water. The arguments for this opinion 
^re forcible. The relics of a variety of fubftances, 
which we now find only in the fea, are found in 
rocks and mountains, at a very great diftance from 
it. In ftrata of lime ftone, every where diftant from 
the fea, we find the remains of ftiells, &c. the pro* 
4u£fcions of the ocean. Other circumftanccs prove, 
that the fea has coviered parts of the earth, which 
^re now at a great diftance from it, and that the vari- 
ous direAions which the ftrata now have were not 
their direftion at their firft formation. That the frame 
of this earth has undergone fome violent concuffion is 
evident, as was already ftated, from the traces which 
ftill remain. The ftrata \ye have feen are often broken 


330 Heater in tbt Center of the Earth. [Book VI, 

in different diitfUons, in general perpendicularly; fi> 
diat the parts of the ftrata are feparated fix>m each 
other. The width of thefe rents is diffcrentj Ibme- 
times a few inches, fomctimes many yards- They 
arc very commonly filled up with fubfiances diffe- 
rent from the com^fidon of the ftrata. In moun- 
tains there is fomedmes obfervcd the appearance of 
a white ftone, which pafles through it like a vein. 
This has been a rent filled up with a particular kind 
of ftone. Thcfc are very common in the ftrata of 
coal* They are generally of confiderable hardnefs^ 
and in them metallic fubftances are ufually found. 
When any of thefe a^e not filled up with extraneous 
matter, the internal furface is fct with very beau- 
tiful and regular cryftals of the Iparry kind, pro- 
jeding into the cavity. 

Some have attributed thefe irregularities to fre- 
quent earthquakes ; others have imagined that the 
globe, before the deluge, contained an imnnenfe 
body of water, covered over with a cruft of earthy 
which at the deluge was broken through, and partly 
funk in the waters, the elevated edges forming die 
mountains and high lands, while the lower were 
overflowed by the ocean j others have fuppoied^ 
that the near approach of a comet has thrown the 
materials of the globe into confufion. Bufi[bn ima« 
gines, that the fea is continually changing its bed, 
and Is conftandy wafhing away the ground from one 
place to another*. But the arguments and obfer* 


♦ A fliort llcetch of the moft remarkable theories of the 

earth 16 given by a popular writer, and it may be amufin^ 

5 t© 

Chap. 43-] ^h0Qry iff the Earth. 331 

vations of Mr. Whitchurft are more defcnr- 
ing attention, fincc he is almoft the only writer 


toJome readers to trace thefe vagaries of the homan imagi- 
nation* ^ 

* The firft who formed thb amufanent of carth-makinginto 
fyftem was the celebrated Thomas Burnet, a man of polite 
learning and rapid imagination. His Sacred Theory, as he calls 
it, defcribing the cj^angcs which the earth hai* undergone, or 
Ihall hereafter undergo, is well known for the warmth with 
which it is imagined, and the weaknefs with which it is reaibn- 
ed, for the elegaitfe of its ftyle, and the meannefs of its philo- 
fophy. The earth, fays he, before the deluge, was very diffe- 
rently formed from what it is at prefent : it was at firft a fluid 
mafs ; a chaos compofed of various fubftances^ differing both 
in denfity and figure: thofe which were moft heavy funk to the 
center, and formed in the middle of our globe an hard folid 
body; thofe of a lighter nature remained next; and the waters, 
which were lighter ftill, fwam upon its furface, and covered the 
earth on every fide. The air, and all thofe fluids which were 
lighter than water, floated upon this alfo ; and in the fame man- 
ner encompaffed the globe; fb that between the furrounding* 
body of waters, and the circumambient air, there was formed a 
coat of oil, and other unduous fubilances, lighter than water. 
However, as the air was (till extremely impure, and mufl have 
carried up with it many of thofe earthy particles with which it 
once was intimately blended, it foon began to defecate, and to 
depofe thefe particles upon the oily furface already mentioned, 
which foon uniting, the earth and oil formed that cruft, which 
foon bep^iQe an )i^bit?ble furface, giving life to vegetation, and 
dwelling to animals. 

* This imaginary antideluvian abode was very different frotk 
what we fee it at prefent. The earth w;^s light and rich; and 
formed of a fubftance entirely adapted to the feeble flate of 
incipient vegetation: it was an uiuform plain, every whera co- 
vered with verdure; without mountains, without feas, or the 
fmalleft inequalities. It had no difference of feafons, for its 
equator was in the plain of th(5 ecliptic, or, in other words, 


331 "Theory of the Earth. ^ [Book VL 

on this futyedy who ^as united obfervation wxch 


n tamed diredlly oppofite to the fan, fo that it enjoyed ace 
perpetual and luxuriant fpring. Ho\vever, this delightful 
face of nature did not long continue in the fame ftate, for, after 
a time, it began to crack and open in EiTHres : a circiunftance 
which always fuccecdt when the fun exhales the moidure from 
rich or marlhy fituations. The cringes of mankind had beea 
for fomc time preparing to draw down the wrath of Heaven; 
and they, at length, induced the Deity to defer repairing theic 
breaches in nature. Thus the chafms of the earth e?ery day 
became wider, and, at length, they pcnettatcd to the great 
abyfs of waters ; and the whole earth, in a manner, fell in. 
'I'hen enfued a total diforder in the uniform beauty of the Kt& 
creation, the terrene furface of the globe bdng broken down: 
as ic funk the waters guflied out in its place ; the delnge be* 
came univerfal ; all mankind, except eight perfons, w^re de- 
ftroyed, and their poHerity condemned to toil upon the roins 
of defolated nature. 

* It only remains to mention the manner in which he relieres 
the earth from this univerfal wreck, which would fcem to be as 
dlilicult as even its firil formation. ** Thefe great maifes of 
earth falling into the abyfs, drew down with thcni vaft quan- 
tiiics alfo of air; and by dajfhing againlt each other, and break- 
ing into fuiall parts by the repeated violence of the fhock, they, 
at length, left between diem large cavities filled with nothing 
but air. Thefe cavities naturally oifered a bed to receive the 
induent waters ; and in proportion as they filled, the face of the 
c^irth became once more viiible. The higher parts of its bro* 
ken furface, now become the tops of mountains, were the hr^ 
that appeared ; the plains foon after came forward, and, at 
kngth, thr whole globe was delivered from the waters, except 
the places in the lowefl fituations ; fo that the ocean and the 
fcas are Hill a part of ^e aacient abyfs that hare not had a 
place to return to. Kkmds and rocks are fragments of the earth's 
former cruft; kingdoms and continents are larger mafies of 
;($ broken fubftance; and all the inequalities that are to be 


Chap. 43-1 ^^^ f '** ^^''*- 333 

With rtfptSt to the form of the carthi ic is now 

fcarcely. neceflfary to mention, that it is nearly 

round ; 

found 00 the forfacc of the prefcnt earth, are owing to the 
accidental confafion into which both earth and waters wero 
then thrown." 

* The next theorift wa« Woodward, who, in his -^Efiky to-, 
wards a Nataral Hiftory of the £arth> which was only defjghed 
to precede a greater work, has endeavoured to give a mora 
rational account of its appearances; and wa^f - in fai£^« much 
better furniihfd for fuch an undertaking than anyof his prcde* 
ceiTors, being one of the moft arduous naturalUh of his time. 
His little book, therefore, contains nUny important faflf» 
relative to natural hiilory, although his fyftem may be we^ 
and groundlefs. 

' He begins by aiTerdng th{(t all terrene fubflances are difpofed 
in beds of various natures, lying horizontally one over the other* 
fomewhat like the coats of an onion; that they are replete with 
(hells, and other productions of the fea: thefe ibells being 
found in the deepeft cavities, and on the tops of the.higheft 
mountains. From thcfe obfervattons, which aiie warranted by 
experience, he proceeds to obTerve^ that thefe fhells and extra* 
aeoas foflils are not productions of the earth, but are all aduat 
remains of thofe animals which they are known to refemble; 
that all the beds of the earth lie under each other, in th|e order 
of their fpecific gnrvity ; anddiat they are difpofed as if they 
bad been left there by fubfidiog waters. All thefe aiTertions he 
affirms with much eameftnefs,. although daily experience con- 
tradids him >ia fomc of them; parcicnlariy we find layers of 
ftone often pver the lighted feilt, a«d the ^ioheSt earth under 
l^e hardeft bodies. However, having taken it -for granted, 
^t all the layers of the earth are found in the order of theif 
fpecific' gravity, the lighteft at the top,'*afnd the heavieft next 
the center, he confequently aflerts, and it wiII'not]mprobab]3^ 
fblk)>w, that all the fubftances of which the earth is compof^d 
were once in an afloal fbte of diifolution. This untverfal dif^ 
Ablation he takes to have happened at the time of the il6od. 
He fttj>polcs that at that time a body of water, which was then 


334 ^^"^ ^^*' Earti. [Book VI* 

tound; a circumftance, however, which, though now 
fo univcrfally known, remained undifcovered fbi* 


in the centef of the earth, uniting widi that which was found 
on the furface, fi) far feparated the terrene parts at to mix all 
together in one fluid mafs ; the contents of which afterwanis 
finking according to their refpedive gravitiesj produced the 
prefent appearances of the earth. Being aware» however^ 
of an obje^ion that fbffil fubftances are not found diflblved« be 
exempts them fiom this univerfal diflblution, and, for that pur- 
pofe, endeaTonrs to (hew that the parts of animals have a ftronger 
cohefion than thofe of minerals; andthat, while even the hard- 
eft rocks may be diflblved» bones and (hells may ftill continue 

' So much for Woodward; but of all the fyftems which were 
publiihed refpefling the earth's formation, that of Whiflon 
was moft applauded, and moft oppcied. Nor need we wonder; 
for being fupported with all the parade of deep calculation, it 
mwed the ignorant, and produced the approbation of fnch as 
would be thought otherwife, as it implied a knowledge of ab* 
firufe learning, to be even thought capable of comprehending 
what the writer aimed at. In hA, it is not eafy to diveft this 
theory of its mathematical garb; but thofe who have had leifore, 
have found the refult of our philoibpher's reafoning to be thus* 
He fuppofes the earth to have been originally a comet*; and he 
cooiiders the hiftory of the crtotion, as given us in fcriptun^ 
to have its conunencement juft when it was, by the hand of the 
Creator, more regularly placed as a planet in ouf fohr fyftem. 
Before that time, he fuppofes it to have been a globe without 
beauty or proportton; a world in diforderi fubjedt to all the 
viciffitndes which comets endure ; fome of which have beeu 
lbttnd,at diffierent times,a thouiand times hotter than melted iron; 
at others, a thoufand times colder than ice. Thefe alternations of 
heat and cold> ^continually melting and freezing the fnrface of 
the earth, he fuppofes to have produced, to a certain depth, 
a chaos endrely refeidbUng that defcribed by the poets, fur* 
rounding the folid ocmtents of the earthy which ftill continued 


Chap. 43,] Vroofs that the Earth ufphmcd. 5jj 

'many- thoufand years. That its form is fpherical, 
was firft conjefturcd from the curved line which 


* unchanged in the midft, makiDg a great baming globe of more 
than two thoufand leagues io diameter. This furrounding 
chaos, however, was ftr from being folid: herefembles it to a 
denfe though fluid atmofphere, compofedof fubftances mingled, 
agitated, and (hocked againft each other; and in thh diforder 
he defcribes the earth to have been juft at the eve of creation. 

' But upon its orbit's being then changed, when it was mere 
regubirly wheeled roynd the fun, every thing took its proper 
place ; every part of the furrounding fluid then fell into a fitua- 
tion, in proportion as it was light or heavy. The middle, or 
central part, which always remained unchanged, ftill continue^ 
fo, retaining a ^art of that heat which it received in its primse- 
▼al approaches towards the fun ; which heat, he calculates, 
may continue for about fix thoufand years. Next to this fell 
the heavier parts of the chaotic atmofphere, whic^ itrtt to 
fuftain the lighter f but as in defcending they could not entirely 
be feparated from many watery parts, with which they virere 
intimately mixed, they drew ddv^ a part of thefe aHb with 
them; and thefe could not mount-again after the furfiic^ of the 
earth was confolidated : they, therefore, furrounded the heavy 
iirft defcending parts, in the Came manner as thefe furround 
the central globe. Thtis the entire body of the earth is com- 
pofed internally of a great burning globe: next which is placed 
an heavy terrene fabibtnce, that encompafles it ; round which 
alfo is circumfufed a body of water. Upon this body of water,, 
the cruft of earth on which we inhabit is placed : fo that, ac- 
cording to him, the globe is compofed of a nun^ber of coata, 
or fhells, one within the other, all of different deniities. The 
body of the earth being thus formed, the air, which is the 
lighted fttbftance of aU> furrounded its furface; and the 
beams of the fun darting through, produced that light which* 
we are told, firft obeyed the Creator's conunand. 

* The whole oeconomy of the creation^ being thus adjofted. 
It only remained to account for the rifings and depreflions on 
the furface of the earth» with the other ^ming iiregularUjes. 


336 • Proofs that the tartb iijpheri^al. fBook Vl^ 

hounds the earth's ihadow in lunar eelipfes. W^ 
Jiarc a ftill pl^iq^ proof of its rottinditjr, from the 


4>f its present appeamiwe. The hills snd tallks are conBdcr- 
ed by him as formed by. th^r preiling upoo the internal fluid, 
<which ifaftains the outward ihell of earth, with greater or leis 
weight; thofe parts of the earth which axe hearieil^ fink into 
the iubjacent Huid more deeply^ and become vallies : thofe that 
are Hgl^ed^ rife higher upon the earth '$ furface^ and are called 

' Such was the face of naxure before ;he delage; the eartb 
was. then more fertile and populous thall it is at present; the 
life of man and animals were extended to ten times its preient 
^uratiop ; and^all thefe advantages arofe from the foperior heat 
.of the central- globe, whifrh ever fince has been cooling. As it^ 
heat was then in full power, |he genial principle was alfo much 
greater than at prcfcnt ; vegetation an4 animal inereafe wersf 
carried: on with more vigour; and all nature feemed teeming 
with the feeds of life. But thefe phyfical advantages were only 
.priodut^ive of moral e.vil; tl^e . warmth which invigorated the 
.body encreafcd the pafiion^ij^id appetites of the mind ; and, a5 
4naA befanie more powerful, hegrewief^ innocents Ic was found 
ivcceffaj-y to puaiih this depravity ; and all living Creatures were 
}9V€;rwhelmed by the deluge in universal dcflru^ion. 
„ « This deluge, whicii fimple believers are wDling to 
^fcribe to a miracle, philofophers have been long deiiroas to 
Account for by natural caufes : they have proved xhzx 
the carih could sever fupply from any reiervoir towards its 
center, nor the aimofphere by any difcharge from above, fuch 
a quantity of water as would cover the furface of the globe to 
4L obrtain depth over the tops of our higheft mountains. Where, 
therefore, was all this water to be found f Whidon has found 
enough; and more than a foAcieacy, in the tail of a comet ; 
for he feefhs to allot conkets t, very, a&ve part in the great ope- 
rations of nature. 

« He calculates with great feeming precvfion, the year, the 

month, aud the dsy of the week gn which this comet (which 

havpaid the earth ibtfie v^t) iinee, though at a J^iiuler diAance) 

4 juivojvcd 

fchap. 43*] S^bertcd Form of the Earth. 337 

appearance of objefts on the furface of the earth, 
but dill more reoiarkably on that of the fea. Ai^ 

i'h^elved Oilr globe in its taU; Thfc tail hi fappofed to be 4 
vapourous fluid fubftance, exhaled from the body of the cOme^ 
by the eietreme heat of the fun> and increaiing in proportion 
as it approached thlt great luminary. It was in this that our 
globe w!ls involved at the time of the dduge ; and, as the earth 
, ftill adhjd fey its natural Jittra'aion, it drew to itfelf all the watery 
Vapours Which weire ib the cbmct's tail ; and the internal wa- 
ters Being alfo at the fatne time Itt loofe, in a very ihort fpace 
the tops of the highbft mountains were laid under the deep. 

The punifhment of the deluge being thus completed, and all 
the guilty deftroyed, the earth, wl^ich had been broken by th^ 
eruption of the internal waters, wits alfo enlarged by it^ fo that 
upon the comet's retefs, there was found room fufficient in the 
internal abyfs for the retefs of the fuperfluout waters ; whither ' 
they all retired, artd left the earth uncovered^ but in fomc rc- 
fpefls changed, pafticUlarly in its figure, whicb> from bein^ 
tound, was now become dblate. In this univerfal wreck of 
% nature Noah furvived, by a variety of happy caufes; to re* 
■ ' people the earth, and to give birth to a race of men flow in be* 
lieving iiUimagined theories of the ekrth. 

After fo many theories of the earth, Which had been pub- 
li(hed, applauded> anfwered, and forgotten, M. Buflbn ven^ 
tured to add one more to the number. This philofopher was 
in every refpeft better qualified than 4ny of his predeceflbrs for 
fuch an attempt, being furnifiied with more materials, having 
a brighter imagination to find new proofs, and a better^flyle to 
doath them in. However, if one fo ill qualified as I am ma/ 
Judge, thi^ feems the weakeH part of his admirable work ; 
and I could wifli that he had been content with giving us fadls 
inllead of fyftems 5 that, inftead of being a reafo^er, he had 
Contented himfelf with being merely an hiftorlan. 

H« begins his fyHem by making a diflindion between the 
lirfl part of it and the laft ; the one being founded only on con- 
jedhire, the other depending entirely upon actual obfcrvation* 

Vol. II. Z The 

338 Spherical Form of the [Book Vl* 

^e depart from objcfts oh the ocean, they fcem to 
fubfide gradually below the vifible horizon. SIups 


The Utter part of his theory may, therefbrcj be. true, thoo^h 
the former fhould be found erroneous. 

The « planets, fays he, and the earth among the number, 
might have been formerly (he only offers this as conjedure) 
a part of the body of the fun, and adherent to its fubftance. 
In this iituation, a comet falling in upon that^reat body migl^ 
have given it fuch a ihock, and fb fhaken its whole frame, that 
fome of its particles might have been driven off like dreaming 
fparkles from red hot iron; and each of thefe dreams of fire, 
£nall as they were in comparifon of the fun, might have been 
large enough to have made an earth as great, nay many times 
greater than ours. So that in this manner the planets, together 
with the globe which we inhabit, might have been driven off 
from the body of the fun by an impuliive force : in this manner 
alfo they would continue to recede from it for ever, were they 
not drawn back by its fuperior power of attraction ; and thua^ 
by the combination of the Wo motions, they are wheeled 
round in circles* 

Being in this manner detached at a diflance from the body 
of the fun, the planets, from having been at firil globes of 
liquid fire, gradually became cool. The earth alfo having 
been impelled obliquely forward, received a rotatory motioa 
upon Its axis at the very inftant of its formation ; and this motion 
being greateft at the equator, the parts there adingagainft the 
force of gravity, .they muft have fwollen out, and given the 
earth an oblate or flatted figure. 

As to its internal fubilance, our globe having once belonged 
to the fun, it continues to be an uniform mafs of melted 
matter,, very probably vitrified in its primasval fufion. But its 
furface is very differently compofed. Having been in the be- 
ginning heated to a degree equal to, if not greater, than what 
coihets are found to fuflain, like them it had an atmofph&re of 
vapours Boating round it, and which, cooling by degrees, con- 
denfed and fubfided upon its furface. Thefe vapours formed* 
according to their different denfities, the earth, the water, and 


chap. '43.] Earth defnonftrated. 22 9 

at a diftance on the water are not vifible in their 
hulls I at a greater diftance> their mainfaik difap* 


the air; the heavier parts falling firft and the lighter remain- 
ing Hill fiifpended. 

Thus far oiir philofopher is» at leaft, as mach a fyftem- 
maker as Whifton or Burnet ; and, indeed, he fights his way 
ytith great perfeverance and ingenuity through a thousand ob- 
je£bions that naturally ari(e. HaVing, at lail, got upon the. 
earth, he fuppofes himfelf on firmer ground, and goes forward 
with greater fecurity. Turning his attention to the prefent ap- 
pearance of things upon this globe, he pronounces from the 
view that the whole earth was at firft under water. This water 
he fuppofes to have been the lighter parts of its former evapo-^ 
ration, which, . while the earthy particles funk downwards by 
their natural gravity, floated on the forface, and covered it for 
« confiderabie fpace of time. 

« The furfece of the earth," fays be •, " muft have been- 
in the beginning much lefs folid chan it is at prefent ; and, con* 
fequently, the fame caujfes, which at this day produce but very 
flight changes, muft then, upon fo complying a fubilance, have 
had very confiderabie efieds. We hare no reafon to doubt but 
that it was then covered with the waters of the fea ; and that 
thofe waters were above the tops of our highefl mountains, fince» 
even in fuch elevated iitnations> we find (hells and other marine 
produ^ons in very great abundance. It appears alfo that the 
fea continued for a confiderabie time upon the face of the 
earth : for as thefe layers of (hells are founcl fo very frequent 
at fuch great depths, and in fuch prodigious quantities^ it feems 
iixqX>ffiUe for fuch numbers to have been fupported all alive at 
one time ; fo that they muft have been brought there by fuc- 
ceffive depofitions. Thefe (hells alfo are found in the bodies 
of the hardeft rocks, where they could not have been depofited 
all at once, at the time of the deluge, or at any fuch infiant 
revolution; fince that would be to fuppofe, that all the rocks in 
which they are found were^ at that infiant, in a ftate of difib- 

f Theorie de la Terre* vol. L p. 1 1 x. 

Z z lution. 

4eo Theory of [Book VI. 

pear; and at a greater dill, their topfails; wlucb 
could not be, if they failed on a plain. But that the 
earth is really globular was at length praftically 
demonftrated by the adventurous projeft of failing 
round it, which has fevcral times been cffcfted. 

This faft being prcmifed, let us confider in what 
manner the known laws of nature were likely to 
ad upon a mafs of nnateri;ds fuch as enter into the 
cpmpo^dfn erf this globe. 

The firft principle of the law of gravitation is, 
that the conftituent particles of all bodies attract each 

Iudon> which would be abfurd to aflert. The Tea, therefore, 
depoiited them where ever they are now to be foandj and thac 
by flow and fucceflive degrees. 

" It will appear^ alfo, that the fta covered the whole earth, 
from the appearance of its layers, which lying regularly one 
above the other, feem all to refemble the fediment formed at 
dllFerent times by the ocean. Hence, by the irregular force of 
its waves, and its currents driving the bottom into fand-banks, 
mountains muft have been gradually formed within this 
vniverfal covering of waters ; ' and theTc fuccefiively raiiiDg 
their heads above its furface, mujl» in time, have formed the 
klgheft ridges of monntuns upon land, together with contioenrs, 
iflands, and low grounds, all in tlieir turns* This opinion will 
receive additional weight by confidering, that in thofe parts of 
the earth where the power of the ocean is greatefl» the inequi* 
lities'on the furface of the earth are highefl : the ocean'< power 
u greateft at the equator, where its winds and tides are mpft 
conflant ; and, in fa^, the mountains at the equator are found 
to be higher than in any other part of the world. The fea, 
therefore, has produced the principal changes in our eanlr: 
rivers, volcanoes, earthquakes, dorms, and rain, having madt 
bnt flight alterations, and only fuch as haye afFe£ied the globe 
to very inconiiderable depths." 

Goldsmith 's Hificrj of the Earth and dnimattd NtOuru 
^ Vol* I. p. %z^ &c. 

5 oihcf 

Chap. 43.] the Earth. ^ . 341 

other mutually, whence arife their coipmon cen- 
ters of gravity. Hence all fluids afliame a fpherical 
form, from the particles mutually attrafting each 
other ; and no bodies but fluids being capable b£ 
<2ibeying the laws of gravitation, fo as to become 
fpherical, it is prcfumed that the earth was origi* 
nally in a fluid ftatc. The earth revolves round iu 
center, and the centrifugal force increafes in propor- 
tion to the diftance from the axis of amotion; all. 
bodies, therefore, revolving round their ^is in a 
ftate of fluidity, will neceflarily depart from the 
fpherical form, and aflfume that of ^p oblate fphe* 
roid. Such, by adlual menfuration, is found to be 
the form of the earth j and this is alfo demonftrated, 
by aflronomical obfervations, to be the cafe with aU 

. the other planets. It is therefore highly probable, 
■y^ that all chefe bodies were originally fluid, and only 
departed in fome meafure from the fpherical form, 
in confequence of a revolution on their aKis. 

It is not natural or eiafy to fuppofe, that the earth 
and planets have, fince their exifl:ence, been reduced, 
by any folvent principle, from a folid to a fluid ftate. 

- It is much more obvious to believe, that; fuch was 
their ftate at their firft creation. It follows of con- 
fequence, that they had a beginning, and have not 
cxifted from eternity, as fome fant^ftical writers 
have been inclined to imagine. 

If fuch was the original ftate of the earth, it fol- 

. lows, that it was at firft abfolutely unfit for aninrial 

and vegetable life; and, therefore, thefe ttiuft have 

been after-creations. This account, it is obiervable, 

agrees admirably with the Mofaic account of the 

Z 3 creation^ 

342 , theory of [Book Vf . 

creation^ as well as with the opinions of the moft 
ancient philo&phers, liiftorians, poets, &c. that isj 
with the traditions of the firft ages. 

It is the opinion of Mn Whitchurft, that the 

.component parts of the earth, at its firft formation, 
cxiftcd in a ftate of aftual fblufion, and that they 

.fubfided pardy into folid bodies, and partly into 
fluids, by the mutual aftion of thefe particles upon 
each other. 

We have feen that there exifts between different 
particles of matter what is called eleftive or chemi- 
cal attraftioiv by which fubftanc^s having certain 
properties in common are difpofcd to unite ; and by 
the combinadons thus formed (whether by an im- 
mediate aft of omnipotence, or whether by fbme. 
more gradual procefs"^ the fufpenfion of the compo- 
nent parts of the chaotic mafs would be cfFcftually 
dcftroyed, and bodies would approach towards 
their center of gravity in proportion to their refpec- 
tivc denfiries. That the laws of eleftive attraftion 
have prevailed in the formarion of the earth is evi- 
dent from the famcnefs of quality which is obferved 
in difft-rent ftrata of minerals. 

It has been, I think, demonftrated* that the pre- 
fcncc of heat or fire is the efficient caufe of .fluidity. 
When the permanently claftic fluids, therefore, 
which conftitute the atmofphere, aflfumed their 
aeriform ftate, and rofe from the chaotic mafs, a 
great quantity of heat muft have become latent, 
while die remaining fubftances, from which the 
heat wa6 abftraSed, muft have been confiderably 
cooled, and it might, therefore, be expc&ed, that 


Chapr4J.] the Earth. 343 

diofe kinds of matter^ v^hich had leaft attraflion foi 
heat, would aiTume a folid for^i; while others^ 
whofe attra<5i:ion for that fubftance was interme- 
diate, would remain in the date of common fluids. 
It is, therefore, perfe£Uy agreeable to found philo-^ 
fophy to fuppofe, that the abftraftion of a confi* 
derable quantity of caloric, or the matter of fircn 
from the chaotic mafs, would effedually deftroy 
its fluidity, and would .^Imoft inftandy produce 
all the different mineral fubftances, which are 
obferved in the bowels of the earth. Not that wc 
are under any necefTity of believing, that the whole 
internaLfubilance of the earth exiffi at this hour as 
it cxifted when creation was completed. There are 
a variety of procelTes going on continually in the 
interior parts of the globe, befidie thofe more fud-^ 
den and violent changes, which have been produced 
by earthquakes, floods^ and volcanoes. 

By the* fubfiding of the denfer and more folid 
bodies, a confiderable portion of the fluid matter 
would be left in a feparate ftate, and would form 
largp maffcs, or oceans of water. 

Witfi refped to the formation of iflands, nothing 
more was ncceffary than the unequal and irregular 
fubfiding of the different parts of matter, which 
may have happened from a variety of caufes; from 
the effefts of elcdlive attraftion and cryftallization i 
from the motion of the earth, and the flux and 
rcfltux of the tides. The latter caufe would necef- 
farily remove the folid maffes, as they were formed, 
from place to place, till thefe folid maffcs, meeting 
with others, or increafing their bylk by their aftion 

Z 4 vpoA 

544- Oripnofljlands. [Book VI, 

upon congenial particles, would, from their incrcafed 
gravity and dcnfity, at length become ftationaiy. 

. Thus the furface of the earth is all irregular, and 
an ifland is no other than a hill or mountain, the 
adjacent vallies of which are filled with water. 
Some iflands, however, we know, arc of more rcr 
cent origin. Some have been thrown up by volca- 
nic eruptions i and fome have apparendy been 
formed by that extraordinary infeft which produces 
rocks of coral. The iflands Delos and Rhodes arc 
faid to have ffrown out of fhe fca. Pliny mentions 
a number of other iflands, which were produced by 
fubterraneous fires. In 16-28, one of the iflands bif 
the Azores rofe up out of the bottom of die fca, 
which in that place was one hundred and fixty fa- 

' thoms deep; and this ifland, which is three leagues 
long, one league and an half broad, and three hun- 
dred and fixty feet above the level of the watCF, 
rofe in fifteen days *. 

On the 20th of November, 1720, a fubterra- 
neous fire burft out of the fea near Tercera, one of 
the Azores, which threw up fuch a' quantity of 
ftones, in the fpace of thirty days, as formed an 
ifland two leagues in diameter, and nearly circu- 

* The Iflc of Sheppey contains a great variety of 
foflil bodies, as well animal as vegetable, which 
cvidendy .prove it to be an aflemblagc of adventi- 
tious matter. 

• Sir William Hanultcn'5 Obfervations on Vefuyius and 

f Philofophical Tran^ifbions^ quoted by WhiteKuril. 

Chap. 43-] ExuvU cf Fijb fcund in the Earth 34J 

i n every inftance upon record, the fragments of feA 
ihells are infinitely more numerous than the bones 
and teeth of fifh. The latter too are but feldom 
depofited in any other matter than in beds of fand 
and gravel, and not in the folidbeds of lime-ftone» 
as the Ihells of fifli generally are, even co the depth 
cf many hundred yards, and difpofed throughout the 
whole extent of the ftrata*. 

There is no occafion to fuppofe, that the whole 
iurface of the earth was at once rendered habitable. 
From the fcripture account we have reafon to believe, 
that only a very fmall part of it was inhabited for a 
Jong feries of time, viz. the regions about the Eu- 
phrates^ fuppofedto conftitute the Garden of Eden. 
Here the terjeftrial animals were chiefly aflembledj 
while the marine animals were difperfed through the 
great^abyis of waters ; and, f]x>m the extremefecundity 
of thofe animals, they would, in a very (hort fpace 
of time *' rcplenilh the waters'' from pole to pole. 
If, therefore, we fuppofe (as is moft probable) 
that the greater part of the earth was graduallf 
forming itfelf according to the laws of nature and 
creation, in other words, according to the ufual pro- 
cefles of attradion and combination, it is ealy to 
conceive, that a part of thele animals, efpecially thole 
which are leaft active, would be gradually intombed 
in the increaGng mafs, and this will account for the 
great quantities of the exuviae and bones of marine 
animals, efpecially fhell fiih, which are found in 
beds of lime-ftone, gravel, &g. even on the tops 
pf moiuitains. 

♦ WMtehurft, p. 44. 


346 Early Cmoul/ms of the Earth. [Book Vf^ 

. Wc fhall ceafe to be aftoniflied at the immenfe 
quantities of (hells, whkh are thus found imbedded 
in the cajth, if we only coniider the amazingly pro- 
lific nature of thefe animals. It is not uncommon 
to take away a bed of thefe fhell fi(h feveral £l- 
thoms in thicknefs ; and> though the places whence 
they are rexsuDvcd appear entirely exhaufted^ yet in 
the enfuing feafon there Axall be as many found in all 
diefe places as there were before *. 

The bones or teeth of fifli, Mr. Whitehurft 
affirms, as far as -his knowledge extends, have never 
been found mixed with fhells in the folid fubAance 
of lime-ftone. 

That at different periods the earth muft have 
ibffered very violent convulfiops and difcerpta- 
tions of the folid parts, we may reafbnably 
conclude from the rugged and uncouth appearance 
of many of the mountainous parts of the world. 
We fee ropks in fome places torn afunder, or, in 
appearance cut with a faw. Mr. Whitehurft remarks^ 
that at Stafford and Newport, in Sbropfhire, there arc 
detached blocks of Cornifh mobr-ftone, or granite, 
.pf cpnfiderable magnitude, though no fuch flratum 
is known to exift nearer than Cornwall. It is &ir> 
therefore, to condude, that they have been thrown 
there by fome violent commption or fubterraneous 

To the general deluge, that faft recorded with fo 
much precifion in the writings of Mofes, and con- 
firmed by the traditions of every nation, we mufl 

* Whitehurft, p. 47. 


Chap. 43.] Proefs of the Deluge. 347 

attribute much of the irrcgularirics of the carth'ii 
furface. It would in fome inftanccs have the cffcfl: 
, of reducing great maffcs of nnatter tp a fecond ftatc 
of folution. Many eminences would be levelled, and ' 
fome of the vallies would be filled up. Some 
parts, which before were fea, might receive (uch an 
accefEpn of foreign matter as to fill up their beds, 
and on the fubfiding of the waters to prefent to the 
eye a vaft level plain. Thofe elevations, on the 
contrary, which confifted of folid maflfes of the 
harder (tones, would have the lighter portions of 
tarth waflied away from their bafes, and their 
height would receive a proportional increafe. If 
pit coal, indeed, is of vegetable origin, it is difficult 
to account for the dcpofition of fuch a quantity of 
vegetable matter beneath the furface of the earth, 
on any other hypothefis than that of a deluge; 
and though much of the exuviae of IhelUfifli might 
, be involved in the firft ages fucceeding the creation, 
in the manner Mr. Whitehurft fuppofes, much 
greater quantities would be inhumed at the deluge. 
The other animal matters found in a toflil ftate, 
particularly the horns, ikcletons, and bones of 
animals, which are much larger than any now found 
upon the earth, can only be accounted for upon 
this hypothefis. Such are thpfe mentioned by 
Bufibn, which were dug up in America, near the 
river Ohio, a fingle tooth of which, belonging to a 
. large row, weighed upwards of eleven pounds, and a 
fingle thigh bone was upwards of four feet in length. 
In the year 178^, a (keleton of m immenfe animal 
pf the deer kind was found on an cftate belonging 


34* Struaure of [Book VI. 

to Dr. Percy, Biflibp of Dromore. It was dug out 
of 2 marie pit, under a peat mofs, and was found 
forrounded by (htills and <fthcr marine produftions. 
The horns were feven feet and one inch in height, 
the length of the fkuU nearly t^vo,feet, the breadth 
efthc forehead nearly a foot, and tho bones ofati 
enormous fize. In Siberia, in America, and even 
in England, the bones and teeth of the elephant, 
ktppopotamus, and other animals, which never 
have cxifted in thofe climates, have been found, 
and even thefe were larger than thofe of any fuch 
anfmals now exifting. 

To the deluge, therefore, much of the prefent 
Bicquali^ies of the earth may be rationally attributed. 
But there are other caufes which may have ope- 
rated both before and fincc. It is a faft, which will 
fcarcely admit of difpute, that volcanic eruptions 
were much more frequent in the early ages of the 
world than at prefent 5 the veftiges of volcanoes , 
and, even the cxhaufted craters, are often found, 
where there is now not the fcaft appearance of fub- 
tcrraneous fire. This faft is alfo eafily accounted 
for on philofophical principles. The imperfeft, 
andy if I may fo fpeak, accidental mixture of difFc- 
lesG bodies, would in many cafes produce fponta- 
Beo«s inflammation in the early ages of the world, 
whereas, as the earth grows older, thefe materials 
inwft be exbaufted, or rather formed into other com- 
binations. Many mountains, we know, are of vol- 
canic origin, and therefore many of thern of ^ dale 
long poftcrior to the sera of creation. 


Cb^. 43-3 the Earth. 349 

/ Such appears to be the moft rational ^account of 
the ftrofture of the earth, as far as we arc warrant- 
ed by aftual experiment, or well authenticated ob- 
fervation. The fuccecding chapters of this book, 
will ferve to explain more fatisfadlorily the different 
appearances of different portions of the globe. I 
(hall therefore proceed, without further digr^fllonj 
to treat more particularly of mountains, volcanoes, 
and the other phenomena more immediately con- 
neftcd with this branch of natural hiftory. 


t 350 1 * [BookVL 

Chap- XLIV. 

DiftinShn ietwan Hills and Mouutaius.^^McitMtains prma^ml or 
j€cmimry,'»^'Graiuie Mountmns mIj /uppofed in gtnertd priwue^oL 
•^OMi Itme^fioni Mountains prim^t^uaL^^jOlnntial IfomdMhu.^'^ 
Entire andjlratified Mountains .'^Mountains bom^gattous and 
beterogentous.'^'Confu/ed Mount ains^'^^Felcanic MonntaiMU^-^ 
Height of Mountains, bofw nua/ured,^^Comput£d Heights of the 
moft remarkahU Mountains^r^Line of Congelation in different 
Parts of the World, 

ELEVATIONS, confifting chiefly of cky,iand, 
or gravel, are called hills. Thofe which con- 
fift chiefly of done are called mountains. Moun« 
tains arc divided into primaeval, that is, of equal 
date wirfi the formation of the globe, and fecondary 
or alluvial. Among primaeval, thofe df granite hold 
the firft place. The highcft mountains and moft 
extenfive ridges throughdut the globe ar« of that 
kind} as the Alps and Pyrcnnecs, in Europe; the 
Altuifchan, Uralian, and Caucafus, in Afia ; and the 
Andes, in America. The higheft of them never 
conuin metallic ores; but fomc of the lower contain 
ores of copper and tin. The granite next the ore 
always abounds in mica. Perrifaftions are never 
found in thefe primaeval mountains. 

That the formation of thefe mountains preceded 

that of vegetables and animals, is juftly inferred from 

their containing no organic remains, either in the 

6 - form 

Chap. 44-i CGmpr^rkn of M9t4ntmns^ 35t 

form of petrifaiftion or imprcflion. Naturalifts are 
figreed, that granites were formed by cryftallization. 
This operation probably took place after the format 
tion of the atmofphere, and the gcadual excavation 
of the bed of the ocean, when the dry land ap^ 
peared* For, as was remarked in * the preceding 
chapters by • means of the feparation of the acrt- 
ibrm fluids, whidv conftitute the atmofpbere, the 
evaporation of part of the water into the atmolphere, 
and the gradual r«:reat of the remainder, the va- 
rious fpeciesf of earths, before diffolved or difFufed 
through this mighty mafsr, were difpofed to coalefce, 
and among thcfe the filiccois muft have been the 
lirft, as it is the leafl: foluble ; but as the filiceous 
earth has an affinity to the other earths with which 
it was mixed, fame of thefe muft have united in 
various propcM-tions,and thus haveforjmed, in diliinfl: 
maflfes, the felt rpar,fliocri,and mica, which compofc 
the granite. Calcareous earth enters very fparingly 
into the compofieion of this ilone$ but as it is found 
in fhoerl, which is frequently a component part of 
granite, it follows that it muft be one of the primi- 
tive earths, and not entirely derived from marine 
exuvias, as fome have fuppofcd. Quartz can never 
be fuppofed to be a produft of fire; for in a very 
low^heat it burfls, cracks, and lofes itstranfparency, 
and in the higheft degree of heat that we can pro^. 
duce, is infufible,/o that in every eflcntial point it is 
different from ^lafs, to which fome have compared 
it. As granite contains earths of every genus,, wc 
may conclude, that all the fimple earths are original* 
This> however, is no proof that they are in feafity 


35^ Prtnuevala^ayeiutHidMamfains. [Book VJL 

fimple and uncompounded of odicr principles ; biit 
they muft be confidered as fuch in the present Hate 
of our knowledge. Though water undoubtedly 
dates from creation, yet late experiments have 
ihewn it to be a compound^ as was formerly dated. 

Mountains* which confift of lime-ftone or marbles 
of a granular or fcaly texture^ and not difpoied in 
ftrata> feem alfo to have preceded the creation of 
animals> for no organic traces are found in thcm^ 
Some of thofc, which confift of argillaceous ftones^ 
and fome of the filiceous, contain alfb no organic 
remains. Thefe often confift of parallel fbata of 
unequal thicknefs> and the lower are harder and leis 
thick than the upper^ and therefore feem to have 
been formed earlier than the upper. 

Alluvial mountains are evidently of pofterior fbr- 
mation> as they contain petrifaflions and other vef- 
tiges of organic fubftances> and thefe are always 

Mountains^ i^s to ftruAure> are entire^ fbadBcd, 
and conflifed. Entire mountains are formed of huge 
mailcs of ftonCi without any regular fifTurefi, and 
are moftly homogeneous. They confift chiefly of 
granite, fometimes gneifs*,fchiftus, fiag-ftone>fand- 
ftone, lime-ftone, gypfum, porphyry or trapp. 
Some in Sweden and Norway confift of iron 

The ftradfied mountains are thofc whofe mals is 
regularly divided by joints or fifTures ; thefe arc called 
horizontalj rifing, or dippings Homogenous ftra-» 

f A rock confifting of mica, lapis oUaris, and qoartz* 


^hap. 44*] Cmpmndftrat^dMcuntahu. ^^i 

tilled mountains confift chiefly of dohes of die ar* 
giUaceous genius, or of the ftflilc compound ipecied 
of die niiceous genus^ as metallic rock; ibmedihea 
of lime-ftone of a granular or fcaly textiire> in which 
no animal Veftiges appear. This lime-ftohe repofes 
bn the argillaceous or liliceous ftrata : ibmedmes 
the argillaceous are coVered with maflfes of granite, 
fomedmes of lava. Thefe mountains, pardcularly 
thofe oFgneifs, metallic rock> and horn-ftone, are 
the chief feat of metallic ores. Whert covered with 
lime-ftoiie, the ore is generally between the lime- 
ftone and the argillaceous ftones. Thefe ores run 
in veinsj not lA (h-ata. Petrifa&ions are found 
upon, but not in^ thefe mountains. 

Heterogeneous, or compoundftratified mountains, 
confift of alternate ftrata of various fpccies of ftones, 
eardis, fands, &c- The lime-ftone here is always 
bf the lamihar, and not of the granular or fcaly kind, 
and when it contains any ofe^ it is placed between 
its laminae. Stbnes of the liliceous genus feldom 
iform iPki'ala in thefe mountains, except lavas; but the 
ftrata are frequendy interrupted by liliceous maflfes, 
as jafper, porphyry, &c. Coal, bitumen, petrifac- 
doils^ and orgaAic imprefllons, are fdtknd in thefe 
mountains, alfo falts and calamine; 
• There are other mountains, which cannot properly 
be called ftrarified, as they confift only of three im- 
menfc maflfesj the loweft granite, the middle argil- 
laceous, and the upper lime-ftone. Metallic ores 
^e found in the argillaceous part, or between it and 
the lime-ftone* 

yoL.IL A a Confufed 

354 'MBde of comptaing [Book VI. 

Confofcd mountains confift of ftones heaped to- 
gether without order, their interftices filled with 
clay, fand, and mica. They fcarccly ever contain 
any ore. 

, Befidcs thefe, there are many mountams in dif- 
ferent parts of the world, which derive their origin 
from volcanoes ; but of thefe it will be neceflary to 
treat in the fucceeding chapter. 

The height of mountains is ufually calculated by 
means of the barometer, upon the principles already 
explained. For this purpo'fe rvvo columns of mer- 
cury, or barometers, are provided, and one is kept 
at the foot of the mountain while the other is carried 
to its fummit. The degree of heat, if not equal, is 
reduced by talculation to an equality, and for this 
purpofe a thermometer is attached to each *of the 
barometers. The degree of heat, to which both are 
reduced, is commonly 55*. If, however, cither of the 
barometers ftands at thirty inches, and the annexed 
thermometer at 55% no reduftion is to be made in 
the degrees indicated by that barometer ; but if cither 
of them is at 30°, and the thermometer below 55% 
we muft add the expanfion the mercury in the ba- 
rometer would have experienced at the heat of 55*. 
If the heat fliould, on the contrary, be above ss% 
we muft fubftraft the degree of expanfion which it 
gains by that heat. Every degree of Farenheit's 
fcale produces an expanfion of co.304 of the baro- 
metrical inch, when the barometer is at 30 ; when, 
therefore, the thermometer is at 1 1*' below or above 
SS^^i we muft add in the former, or fubftraft in the 


Chap. 44.J the Height of Mountains* 3^5 

latter cafe, eleven times that niimbei-frbrh the taro* 
metrical height. In the fame manner it may be cal- 
culated, whatever is the height df the barometer. 
When this matter is afcertained, the lieight is eafily 
* found by comparing the two barometers, and cal- 
culating the denfity of the air in the higher regions 
according to the principles of geometrical progref- 

The higheft mountains are thofe which are fitu- 
ated at or near the equator; and the Andes are ge- 
nerally allowed to be the higheft of thefe. Cato- 
paxi, one of the Andes, which was mcafured .by 
UUoa and the French academicians, was found to 
be rather more than three miles above the level of 
the fea ; whereas the higheft point of the Alps is not 
above a mile and a half. Mount Caucafus ap- 
-proaches >neareft to the height of the Andes of any 
of the Afiatic mountains. The Pike of TenerifT^ 
which has been fo much celebrated, is about a mile 
and a half in height. It is an extraordinary cir- 
cumftance, tliat the moon, which is a body fo much 
fmaller than our earth^ fhould fo greatly exceedjt 
in the irregularities of its furface j fome of the 
mountains in that planet being calculated to' exceed 
nine miles in height. 

The line of congelation, or perpetual froft, on 
molmtams, is calculated at 15,400 feet, at or near 
the equator -, at the entrance of the temperate zone, 
at 13,428 i on Teneriffe, at 1,000 j in Auvergne 
(lat. 45.) 6,740 ; with us (lat. 52.) 5,740. On the 
Andes, vegetation ceafes at 14,697 feetj and on 
A a 2 the 

3 $5 Line of perpetual Frofi. [Book VL 

the Alps, at 91585. The air is fo dry in thefe ele- 
vated fituadons, that M. D'Arcelobferred, that on 
die Pic de Midi, one of the Pyrenees, fait of tar- 
tar remained dry for an hour and a half, though it 
immediately moiftened in the fame temperature at 
the bottom of the mouDtaia. 

Chap. 45j ■ { 357 3 

Chap. XLV. 

General Ohfervatiom on Volcanoes. ^^Their Connexion lohb the Sea, 
''^Immen/e Force of fuhterraneous Fires exemplified in various 
lnfiances,^'Theory of Volcanoes j^^Great DeptL^-Traces ofVol^ 
canoes in different Parts of the World.'^^Defcriftion of JEtna^^^^ 
Eruption of Vefii<vius, in 1794. 

VOLCANOES are peculiar to no climate, and 
have no ncceflary or regular connexion with 
any other mountains, but fcem to have fome with 
the fca, for they are generally in its neighbourhood. 
It has been remarked by thofe who have obferved 
them, that volcanoes often throw out matters which 
belong to the fea, as the relics offifli, fea-weed> and 
often immenfe quantities of fea-water itfelf. Sir 
William Hamiltoh obferves, in the Philofophical 
Tranfaftions for the year 1776, " tfiat the opera* 
tions of Vefuvius are Very capricious and uncertain, 
except that the fmoke increafes confiderably and 
conftantly when the fca is agitated, and the wind 
Wows from that quarter/* 

There are ancient extinguifhed volcanoes, fit i& 
true> which are inland j but this is only one of many 
proofs ih^t the fca covered thofe countries at fomc 
remote period. Volcanic mountains are of all 
heights I fome fo low as four hundred and fifty feet» 
as that of Tanna ; Vefuvius is three thoufand fix 
hundred feet high, and' ^tna eleven thouiand« 
A a 3 They 

358 "tbi Cratep. [Book VK 

They in general form lofty fpircs, and the volcano 
itfclf is internally fhaped like an inverted conCa 
placed on a broader bafis. Thi^ cone is called the 
crater, or bowl, and through it rhe lava generally 
pafles, though fometimes it burfts through the fides, 
and even proceeds occafionally from the bottom of 
the mountain. Sometimes the crater falls in and is 
effaced^ fometimes, in extinguished volcanoes, it is 
filled with water. Sub-marine volcanoes have been 
obferved, and from thefe fome iflands have derived 
their origin. Volcanic fires, taking place at the 
bottom of the ocean, would frequently, by the cx-s 
panfiv(s force of the fleams which are generat- 
ed, elevate thofe parts which were once at the 
bottom of the deep, and overflow thofe which 
were habitable earth. It is yery^ probably con- 
jeftured, as was noticed in a preceding chapter, 
that fubterraneous convuKions operated more 
powerfully in the early ages of the world than at 
any later period ; and indeed fuch an hypothcfis is 
fupported by the moft probable reafoning, fincc 
'wc may well conceive, that at the firft con^lida- 
tion of the earth, much heterogeneous matter 
would be included in the different mafles, which 
might produce more frequent fermentations than at 
any after periods, when thefe have been, if I may 
fo exprefs it, purged ofi^ by frequent eruptions, and 
in many parts, perhaps, rcftified and affimilated by 
flow and fecret proceffes in the bowels of the eardu 
But hiftory was not cultivated till a very late period, 
and the moft eventful ages of nature have paffed 


Chap. 45.] Force of Volcanic Fires. 359 

The force of fubterraneous fires/ or rather of the 
fteam which is generated by them, is fo great, that 
confiderable rocks have been projefted by Vefuvius 
to the diftance of eight miles. A (tone was once * 
thrown from the crater of that volcano twelve 
miles, and fell upon the Marquis of iTauro's houfc 
at Nola, to which it fet fire. One alfo, which 
meafured twelve feet in height and forty-five in 
drcumference, was carried, in 1767, bj^ the projec- 
tile force of the fleam, a quarter of a mile from ' 
the crater. In an eruption of ^tna, a done, fifteen 
fcet long, was ejedlcd from the crater to the dif- 
tance of a mik, and buried itfelf eight feet deep- 
in the ground. 

A volcano broke forth in Peru, in 1600, ac- 
companied with an earthquake, and the fand 
and aflies which were ejefted covered the fields 
ninety miles one way and one hundred and twenty 
another. Dreadful thunders and lightning were 
heard and feen for upwards of ninety miles round 
Araquapa during this eruption, which fecmed to 
denote fomc conneftion between the eledric matter 
and thefe volcanic fires * j and this faft is ftrongly 
confirmed by the very accurate obfervations of Sir 
William Hamilton, which I fhall afterwards have 
occafion to notice more at large. 

Both the infide of the crater and the bafis of many 
volcanoes confift of lava, either entire or decom- 
pofcd, nearly as low as the level of the fea, but 
they finally reft either on gi^anite, as in Peru, or 
fchiftus, as the extinguiflied volcanoes of Heffe and 
Bohemia, or on lime-ftone, as thofe of Silefia, 

* Pr. Hooke's pofthumous Works, p, 304. 

A a 4 Mount 

3^0 Suppojed Caufi of Volcanic Fires. [Boo]( Vl« 

Mount Vcfuvius, &c. No ore is found in thcfe 
mountabsj except that of iron^ of which lava con- 
tains from twenty to twenty-fivc parts in die hun- 
dred, and fome detached fragments of the ores of 
copper, antimony, and arfcnif. Vefuvius ejcdtcd, 
from the year 1779 to 1783, 309,658,161 cubic 
feet of matter of different kinds ; we muft there- 
fore conclude the feat of thefe fires to be feveral 
miles, perhaps hundreds of miles, below thfe level 
of the feaj and as iron makes from one-fourth to 
one-fifth of thefe ejcftions, we may infer that 
the internal parts of the earth abound much in this 

The origin of thefe fubterraneous fires is not 
^afily explained. Iron filings mixed with powder- 
ed fulphur, and the \^hole moiftened with water 
into a pafte, we have formerly feen, will fwell, be- 
come hot, and, if the quantity is confiderable,*wiIl. 
throw out a blue fiame. It is a mixture of this kind 
which is ufed for making an artificial earthquake, far 
fuch a quantity of inflammable gas is produced dur- 
ing the fermentation, that if the mafs is buried in the 
esuth, the gas will forceapaffage for its efcape, and 
exhibit, on a fmall fcale, the phenomena of an earth- 
quake. M. Lemery fcems to have been the firft 
perfon who illuftrated, in this manner, the ori- 
gin of volcanic fires and earthquakes* He mixed 
twenty-five pounds of iron filings with zr equal 
weight of fulphur, and having made them into a 
pafte with the addition of water, he put them into, 
a pot, covered them with a cloth, and buried them 
a foot under ground. In about eight or nine hours 
time the earth fwelled, became warm, and cracked, 


Chap. 45.1 jfrf^ctd VoUan9. 361 

and hot fulphureous vapours were perceived •• 
Now, large beds of martial pyrites, which are natu- 
ral combinations of iron and fulphur, are known to 
fxift in different parts of the earth i the onljrdiffi- 

♦ That par^ of this experiment (faysBifliop Watfon) which 
felatet to the produdtion of fire, by the fermentation of iron 
flings and fulphur when made into a pafte> has been frequently 
ITpeated fince the time of Mr. Lemery. I myfelf have made 
it more than once, but I have nothing jnaterial to add to his 
account, except that the flame, wheh the experiment is made 
IB the open air, is of very fhort duration ; and that the whole 
ipafs, after the extinction of the flame, continues at intervals, 
for a longer or ihorter time, according to its quantity, to throw 
out fparks ; and that a ladle full of the ignited mafs, being 
dropped down from a confiderable height, defcends like a 
ihower of red-hot afhes, much refembling the paintings of the 
eruptions of Mount Vefuvins, which may be feen at the Britifli 
Mufenm. It has been obferved, that large quantities of the 
materials are not requiiite to make the experiment fucceed, 
provided there be a due proportion of water : half a pound of 
fteel filings, half a pound of flowers of brimftone, and four- 
teen ounces of water, will, when well mixed, acquire heat 
enough to make the«mafs take fire. 

Tha|j heat and fire (hould be generated from the ipontaneous ' 
actions of numrab upon each other, is a phenomenon by no 
means fingular in nature, how diflicult foever it may be to 
account for it. The heat of pntrefcent dunghills, of the 
fermenting juices of vegetables, and, above all, the Sponta- 
neous firing of hay not properly dried, are obvious proofs that 
'vegetablis poflefs this property as, well as minerals. In both ve- 
getables and minerals, a defiinite quantity of moifture is requifite 
to enable them to commence that inteftine motion of their parts* 
vrhich is neceflary for the produdlion of ^, Iron and fulphur 
would remain mixed together for ages without taking fire, if 
they were either kept perfcdUy ixt^ from moifture, or drenched 
with too much water; and vegetables in like manner, which 
are quite dry, or exceedingly wet, arc incapable of Uking 
ire whiUt they contiaue in that fiate. 


26a How Volcanic Fires may befufported. [Book VL 

culty which attends this explanation of the origin 
of volcanoes, as well as of earthquakes, is, that the 
prefcnce of air is in general neceflary for the pro- 
duftion of aftual flame. It is well known, how- 
ever, that niartial pyrites, when nnoiftencd, ac- 
quire heat; and if we fuppofe the'heated pyrites to 
have been in contaft with black wad and petroleum, 
we may fuppofe the flame to arife, as we fee it pro- 
duced by art, from the deficcation of the former fub- 
ftance, and its mixture with mineratoil. Many mine- 
rals, when heated, afford vital air,a veryfmallquantity- 
of which is fufficient to produce flame; this flame, 
once produced, may be fupported from other ores, 
and the combuftion be maintained by the prefcnce 
of bituminous fchiftus, bitumen, and coal. Marf, 
fchiftus, horn-ftone, flioerl, with a further addition 
of ir/on, are the true fources of lava. It fccms, 
however, after all, difficult to conceive that fuch 
cxtenfive and intenfe fires fhould be maintained 
without the accefs of confiderable quantities of air j 
that fubfl:ance may therefore be pofllbly fupplied by 
a communication witli fome extenfive caverns, which 
may thcmfclves receive it by openings at the dif- 
tance of many miles from the crater of the volcano. 
It does not feem iniprobable that the volcanoes, 
which now burn, may have a communication with 
the cavities and craters of extinguilhed volcanoes, 
and thence derive a fupply of air fufficient to ac- 
count for the inflammation of large beds of pyrites 
and bituminous matters. M. Bufibn fuppofcs, that 
the feat of volcanic fires is fituatcd but a very litdc • 
way below the bed of the mountains > but it ap. 


Chap. 45.] General Ohjervatims on Vokanoes. 36 j 

pears more probable, that it is in general many miles? 
below the furface of the earth, for the quantity of 
matter difcharged from ^tna alone is fuppofed, on 
a moderate calculation, to exceed twenty times the 
original bulk of the mountain, and therefore could 
not have been derived from it contents alone, but 
alfo from the deeper receffes of the earth, 

M. Oindamine-aflerts, that all the mountains in 
• the neighbourhood of Naples exhibit undoubted 
marks of a volcanic origin.^ He 6ys, he could trace 
the lava, and other produftions of fubterraneous fire, 
from Naples to the very gates of Rome, pervading 
the whole foil, fometimes pure and fometimes dif- 
ferently combined. " Wherever I fee,'* fays he, 
'^ on an elevated plain, a circular bafon, furrounded 
with calcined rocks, I am not deceived by the 
verdure of the adjacent fields ; I can difcover, be- 
neath ti.e fnow itfelf, the traces of an extinguilhed 
fire. If there is a breach in the circle, I ufually 
find out, by following the declivity of the 
ground, the traces of a rivulet, or the bed of a tor- 
\rcnt, which feems as if it was lioUowed in the rock, 
and jhis rock appears frequently to be pure lava. 
If the circumference of the bafon has no breach, the' 
rain and fpring waters, which are colleded there^ 
generally form a lake in the very mouth of the vol-' 
cano." The Apennines, as well as the Cordeliers of 
Peru and Chili, he fuppofes to have been a chain of 
volcanoes. The chain in both inftances is inter-v, 
rupted, and many of the fires either extinguifhcd or 
fmothered, but many remain ftill aftually burning. 
Tfhis intelligent author is^ however, far from attri- 

364 traces of Volcanoes in Infand. [Book Vf* 

buting to all mountains the fame origin ; and ackis, 
that in that port of the Alps, which he travelled 
over, he could obfcrve no fuch appearances^ 

The traces of vdcanocs have been obferved in 
Ireland by Mr. Whitchurft. Though no vifiUc 
crater is remaining between Port Ru(h Strand and 
Bailey Caftle caftward, yet, he obfcrves, that whole 
fpace, about twenty Englifh miles, is one contimied 
mafc of lava. The cliffs, he fays, are truly ftu- 
pendous, and bear every poffibic mark of having 
been originally liquid fire. The elevation of that, 
at the foot of which the Giant's Caufcway is fituat- 
cd, he prefumes cannot be lefs than five or fix hufi- 
dred feet perpendicular above the level of the Atlan- 
tic ocean, and yet compofed entirely of lava ; the 
fame appearances extend cowards the fouth upwards 
of twenty miles. 

The moft remarkable volcanoes in Europe are 
^tna and Vefuvius, and as thefe are not too far 
ijiftant, we have the moft accurate dcfcriptions of 
them from travellers of the firft talents and reputa- 

* ^tna, which is the moft ftriking obje5t in Si- 
cily, and indeed one of the moft magnificent pro- 
duftions of nature, arifes from an immenfe bafc, and 
mountis equally on all fides to its funimit. The af- 
cent on each Cde is computed at about thirty miles, 
and the circumference of its bafe, at one hundred 
and thirty-three ^ but as it has never been meafurcd 
with any great degree of accuracy, its dimenfions 
are but impcrfeftly known. 

6 ^ ' The 

Chap. 45.] • Defcription of Mtna. 365 

* The whole mountain is divided into three diftinft 
regions, called La Regime Cultu^ or Piedmontefiy the 
fertile regions; LaRegiona Sylvofa^ or Nenwrofa^ the 
woody region 5 and ha Regiona Ikfsrta, or iioperta^ 
the barren region. Thefe differ as materially both 
in climate and production as the tnree zones of the 
earth, and perhaps with equal propriety might have 
beert ftiled the torrid> the temperate^ and the frigid 

* The firft region ofiEtnafurrounds thebafeof the 
mountain, and conftitutes the nK)ft fertile country in 
the world on all fides of it, to the extent of fourteen 
or fifteen miles, where the woody region begins. It 
is compofedalmoft entirely of lava, which, in timej 
becomes the moft fertile of all foils, but the roads> 
which are entirely over old lavas, now converted into 
orchards, vineyards, and corn-fields, are very exe- 
crable. The lavas, which form this region^ arife 
from a number of beautiful little mountains, every 
where fcattered over the immenfe declivities of 
^tna. Thefe are all either of a conical or femi- 
fpherical figure, and are in general covered with • 
beautiful trees, and the moft luxurious verdure. The 
formation of them is owing to the internal fires of 
iEtna, which i;aging for a vent, at fo vafl a diftance 
from the great crater that it cannot poffibly be carried 
to the height of twelve or thirteen thoufand fcetj 
which is probably the height of the fummit of ^ma^ 
muft necefTarily be dlfcharged at fome other orifice. 
After fhaking the mountain, and its neighbourhood 
for fbme time, at length the fire burfls open its fide^ 
and this is called an eruption. At firft it emits only. 

a thick 

266 Defcription of jEtna. [Book VX» 

a thick fmoke and Ihowcrs of afh^s. Thefe are fol- 
lowed by red hot ftones, and rocks of a great Xizc, 
which are thrown to an immenfe height in the air. 
Thefe (tones, together with the quantities of afhes 
difcharged at the fanne time, form thofe mountains, 
which cover all the declivities of IEtc\z. The fizc 
of them is in proportion to the duration of the erup- 
tion* When it continues a confiderable time, it 
fometimes forms an elevation of one thoufand feet 
in perpendicular height, which at its bafe is feven or 
eight miles in circumference. 

* After the formation of the new mountain, the lava 
commonly burfts out from its lower fide, and^fwcep- 
ing every thing before it, is generally terminated 
by the fea. Sometimes it iflues from the fide of the 
mountain, without thefe attending circumflances, 
which is commonly the cafe with the eruptions of 
Vefuyius, in which the elevation being fo much 
fmaller the melted matter is carried up into the cra- 
ter, where it is diflodged without forming any new 
mountain, but only adding to the height of the old 
one ; till at length the lava, rifing near the fum- 
mit, burfts the fide of the crater. But iEtna being 
upon a much larger fcale, one crater is not fuffi- 
cicnt to give vent to fuch immenfe oceans of liquid 

* At Nicolofi, which is only twelve miles up 
i the mountain, tlie climate appears totally changed. 

When the heats at Catania are infupportable, and the 
harvefl: entirely over, the temperature of the air is 
moderate at Nicolofi, and in many places the com 
quite green. Mr. Brydone, in travelling ovcr-ffitna, 


€hap. 45.] Mr. Pryionis Vifit to Mtna. 367 

was ftruck with the degree of wildnefs and ferbcitf 
which appeared in the inhabitants of the mountain, 
and which reminded him of an obfervation made by 
the Padre della Tore, the hiftoriographer of Mount 
Vefuvius, that in places where the air is raofl: im- 
pregnated with fuiphur and hot exhalations, the pco«» 
pie are always moft wicked and vicious. It was with 
great difficulty he could perfuade the people of Ni- 
colofi to fufFer his guide to attend him in the profe- 
cution of his refearches. They were exceffivelj 
troublefome, and extremely fulpicious that his views 
were directed to the difcovery of fome hidden trea- 
fure, the only motive to which they could afcribe fo 
fatiguing ajourney. At length one of them recol- 
kfted having heard many of their old people fay, 
that the Englifh had a queen that had burnt in the 
mountain for many years- paft, and imputed the 
vifits of feveral of that nation co their refped to their 
deceafed fovereign. Upon eaquiring who this queen 
was, they faid her name was Anna, that Ihe was 
wife to a king who had been a chriftian, but (he had 
made him a heretic, and was condemned to burn for 
ever in Mount ^tna. As this could only relate to 
the unfortunate Anne Bullen, Mr. Brydone alked if 
Ihe was the vi6lim alluded to, and whether her huf-i 
band was not likewife condemned to the fame pu- 
nifhmcrit. " Certainly,'* faid the man, " and all his 
heretic fubjeds too ; and if you are of that nupfiber 
you need not be in fuch a hurry to get there, you 
will be fure 6f it at laft." • 

* The beautiful country of Hybla, in the neigh- 
bourhood of Nicolofi, after repeated viciflitudcs, is 

368 JEntpticns of Mtneu [Book VL 

^ how reduced to a melancholy monliinent of the fory 
of -ffiltna ; it was fb much celebrated for its fertilityi 
and particularly for its honey, that it was called Md 

• iiPafli^ till it was overwhelmed by the lava of ^tna^ 
and became totally barren, when, by a kind of pun, 
it obtained the name of Mai Pafli. On a fecond 
eruption, however, a fertile fhower of afties rcftored 
its priftine beauty, and its fornrier appellation. But 
in the dreadful eruption of 1 669 it was again reduced 
to the rtioft deplorable ftcrility, fincc which it is once 
ftnore known by the name which denotes its wiretch- 
cdnefs. The eruption that firft deftroyed diis beau- 
tiful country, iffued from Montpelieri, which it dien 
formed. It deftroyed a great number of villages 
and palaces, and in particular two noble churchest 
which are extremely rcgreted on accouht of three 
ftatues, accounted, at that time, the moft perfcft iii 
the iflandi They have attempted to recover them^ 
but in vain> nor is it believed they ever can; for the 
churches were bwilt bf lava, which is fuppofed to melt 
as foon as it comes into contaft with a torrent of 
hew erupted matter. Maffa, a Sicilian author of great 
credit, affirms, that in fome eruptions of ^tna, the 
feva has poUred down with fuch a fudden impctuo- 
JGty, that, in the courfe of a few hours^ palaces^ 
churches, and villages, have been entirely melted 
down, and the whole run off in fufion. It is how^ 
tVer prpbable, that the impetuous force of the tor- 
rent, rather than its incorporating with the old mafi* 
may in many of thefe inftanceshave occafibned this 
devaftation; Thus much at leaft is certain j that if 



Ghap; 45**l ^ HeJcripHon cf Mtna. jSp 

the lava has had iahy confideniblc time to (?ool, thrs 
Angular efFcift never happens. 

The contraft between the different regions of iEtfi^ 
Js extremely ftrikin^. Oft feAteririg intd the romantic 
forcfts of the Reglone SylVofa, a new creation feem^ 
to arife. The air, which before was hot and fultry, 
is cool apd rcfrefliing, and every breeze loaded 
with delicious perfumes from the aromatic plants, 
with which' the whole ground is covered. Indeed 
every beauty, artd every horror irt nature, feems to be 
United on this wonderful mountain, and the moft op- 
pofite and diflimilar objefts arc promifcuoufly blend- 
ed togetheh Here we obferve a gulph which threw 
but torrents of fire, now covered with the moft luxu- 
rious verdure. Delicious fruits arifmg froiti what was 
but lately a black ia.nd barren rock. Delightful 
flowers tovering the earth, the furface of which Is 
but a few yards removed from lakes of liquid 
fire and brimftone. An immenfe gulph of fire for 
ever exifting in the midftoffnoWs which if has not 
the power to melt, and immenfe fields of fnow and 
ice .unceafingly furrounding this gulph of fire which 
they have not the power to extinguifh. • 

The woody region of ^^tna afcends for about eight 
or nine iYiiIes> and forms a zone of the brighteft 
green around the mountaini In this region^ near the 
^pelonca del Capriok^ or goats cavern, are two of the 
moft beautiful mountains that adorn the fides of-Sltna. 
Their hollow craters arc each of them confider- 
ably larger than that of Vcfuvius. They are now 
filled with ftately oaks, and covered with the richeft 
foil to a great depth. A moimtain at fomc diftance 

Vol. II. B b which . 

^ OatirifjEtMf^ [BookVL 

which was formed by an eruption in 1766, was, ia 
177O9 ftill on firej nor was the lava by any means 
cold This region of ^tna, like the Regme Cuba, 
is compoled of lava ; but this is now covered with lb 
deep a layer of earthy that it is no where to be leea, 
except in the beds of the torrents» in many of which 
it is worn down by the water to the depth of fifty 
or fixty feet, and in one of diem confideraUy more* 
On approaching La Regume Scoptrtay die trees 
begin to afilime a wintry appearance^ and every ob- 
jefl: mdicates the proximity of barrenncfs and eter- 
nal froft 

On completely bidding adieu to the vegetable re* 
jgi6ns, an expanfe of ice prelcnts itfelf, which is fuf- 
.ficient to ftagger the mod determined refolution« 
Above thefe the high fiimmit of the mountain rears 
its tremendous headj vomiting torrents of thick 
fmoke. The difficulty of afcending this part of die 
mountain is gready increaled by the uncertainty of a 
fecure fooung i for the fur&ce of the mountain being 
hot below, frequendy melts the fiiow in pardcutar 
Ipots, and forms pools of water where it is impoffibic 
to forcfee the danger ; fbmenmes, likewife^ it hap- 
pens that the furface of the water, as wcU as the 
fnow, is Covered with black afhes, which reader it 
exceedingly deceitful. At Hrft the afcent is not ib 
fteep, but it becomes fb by degrees. In this region 
are the remains of an ancient fbudure called U 
S^orre del FUofofo^ and fuppofed to have been built 
by Empedoclesy a nadve of Agrigentum, who is 
faid to have died 400 years before the chriftian era. 
His vanity, perhaps, rather than hisphilofophy,led 


Chap. 45^3 Gftat Eruption 9} Mtm. ^'fi 

him to this elevated fituation. Defirous of being 
regarded as a god, lie is recorded to have thrown 
himfelf into the great gulph of ^tna^ in hopes that 
the people would imagine he had been taken up tQ 
heaven, and hcrvcr fuppofmg that his death would be 
difcovered to mankind. But the treacherous ttioun* 
tain threw out his flippers, which were of brafs, and 
announced to the world the fate of the pretended 
phibfopher, who preferred an airy &me, which he 
was beyond the reach of enjoying, to the folid adr 
vantages of exiftcnce, and who was content to pur^ 
chafe the admiration of an ignor^t multitude with 
the meannefs of deceit, and the facrifice of life. * 

Many ftrlking remains of the great eruption in 
1669 are ftill to be feen, and will long continue as 
memorials of that dreadful event which overwhelmed 
Catania, and all the adjacent country^ Tremendous 
earthquakes (hook the ifland, and loud fubterraneous . 
bellowings were heard in the mountain. During 
fome weeks> the fun ceafed to appear, and the day 
feemed changed into night. Borellh who was a 
witnefs to thefc terrible phenomena, fays, that at 
length a rent, twelve miles in length, was opened in 
the mountain, in fome places of which, when they 
threw down ftones, they could not hear them reach 
the bottom. Burning rocks, fixty palms in length, 
-were thrown to the diftance of a mile, and lefler 
&ones were carried three miles. After the moft vio* 
lent ftruggles, and a fhaking of che whole ifland, an 
immenfe torrent of lava guflied from the rent, and 

* See prefent ftate of Sicily and Malta. 

B b 2 iprung 

37^ Vinefard moved from Its Place., [Book VI • 

Ipning up into the air to the heighth of fixty palms, 
whence it poured down the mountain, overwhelm- 
ing every objeft in its way in one promifcuous^ 

This deftruftive torrent, which burft from die 
fide of -flStna at a place called Ricini, rufhed impe- 
tuoufly againft the beautiful mountain of Moncpeli- 
cri, and pierced into the ground to a confiderable 
depth; then dividing and furrounding the mountain, 
it united again on the fouth fide, and poured defola- 
tion upon the adjacent country. The progrefs of the 
torrent was at firft at the rate of feven miles a day, 
but it afterwards took four days to travel fixtccn ; 
wherever it direfted its courfe, the whole appearance 
of nature was changed, feveral hills were formed in 
places which were formerly valleys, and a large lake 
was fo entirely filled up by the melted mafe, as not 
to leave a veftige remaining. In its courfe it dc- 
fcended upon a vineyard, belonging to a convent of 
Jefuits, which was formed upon an ancient and pro- 
bably a very thin layer of lava, with a number of 
caverns and crevices under it. The liquid mafs en- 
tering into thcfe excavations foon filled^hem up, and 
by degrees bore up the vineyard, which in a ifhort 
time, to the great aftonilhment of the fpeftators, 
began to move away, and was carried by the todCnt 
lo a confiderable diftance. In 1770 fome remains 
of this vineyard were ftill to be fcen, but the greater 
part of it was entirely deftroyed. 

In vain did the terrified inhabitants of Catania 

recur for proteftion to the miraculous vei|, or expcft 

. defence from the lofty walls of their city- After 

^ ^ dcftroying 

Chap« 45»] City ever/lowed. ff?itb Lava. 373 

deftroyilig fevefal convents, churches^ and villages, 
this fiery current direfted its courfe to Catania, where 
it poured impetuoufly over the ramparts, which arc 
near fixty feet in height, and covered up five of its 
baftions, with the intervening curtains. After lay- 
ing wade a great part of this beautiful city, and en- 
tirely deftroying feveral valuable remains of antiquity, 
its further progrefs was (topped by the ocean, over 
whofe banks it poured its dcftruftive current. In 
its courfe from the rent in the mountain, till its ar-r 
rival in the fea, it is faid to have totally deftroyed the 
property of near thirty thoufand perfons. 

Still however did the infatuated inhabitants of Ca- 
tania adhere to the remains of their almoft ruined 
city, nor did even the more dreadful calamity with 
which they were afterwards vifited, abate their at- 
tachment. Twenty- four years after the fatal erup- 
tion of 1669, a violent earthquake, which extended 
along all the eaitern coaft, and deftroyed in one hour 
more than fixty thoufand perfons, overthrew the re- 
maining buildings of Catania, and buried a very 
confiderable number of its inhabiunts under the 
ruins of their houfes and churches ; but again the 
place was rebuilt, a new and elegant plan was adopt- 
ed, and the city is now much handfomer than be- 
fore. The principal ftreets are wide, ftrait, and 
well paved with lava. The cathedral, which was 
founded in the year 1094, has fuffered fo greatly 
from earthquakes that a very fmall part of the 
original ftrudure remains. The other religious edi- 
fices are profufely ornamented, but in a bad tafte. 

Bb 3 But 

^•;4 A&i^«/ Vefuvius. [Bdok VI, 

But if the Uftitcd cffefts of attachment to their 
native foiU 'of conteinpt for dangers w which they 
are habituated, and of confidence in the miraculous 
veil, haveoccafioned the wonderful adherence of the 
Catanians to this dangerous fituation fronn which they 
have io fcvcrely fuffered, it muft, however, be con- 
felTed that they have fometimes derived advantages 
from the very evils which they have fo much reafbn 
to dread. Th^y were always in great want of a port, 
with which they were furniftied by one of thofe ca^ 
pricious changes which nature fo frequendy makes 
in this ever varying fpot. A dream of lava runn'mg 
into the (ea, formed a mole, which no expence could 
have furnifhed them with. This advantage, how- 
ever, proved but temporary; there remained fop 
fome time a fafe and commodious harbour, but by 
a llibfcquent eruption it was entirely filled up and 

The 'celebrated Bifhop Berkeley has dcfcribed an 
eruption of Mount Vefuvius, of y^^hich he was a wicnefs 
in die year 1717, and the reader will find his narra- 
tive in tlie firft volume of Dr, Goldfmith's Hiftory 
bf the Earth and Animated Nature, p. 94. But the 
moft complete and philofophical account of this moft: 
formidable phenomenon, a volcanic explolicn, is 
that with which Sir William Hamilton has favoured 
the publicj in defcribing the late dreadflU eruption 
of that nrrountain in 1794; and this I fhall endeavour 
to give, as nearly 33 poffible, in his own words. 

Sir William begins his narratiVe with remarking, 

that the frequent flight eruptions of lava- for fome 

'^years paft had ifTued from near the fummit, and ran 


Chap. 45.] Latt En^Am rf Vidimus. 375 

in fmall chaAneb in di^rent diredions down the 
flanks of the mountain, and ^m running in co« 
vered channels, had often an appearance as if they 
caine immediately out of the fides of Velu\rius, but 
fuch lavas had not fufficient force to reach the cul- 
tivated parts at the foot of the rhountain. Jn the 
year 1779, riw whole quantity of the lava in fufion 
having been at once thrown up with violence out of 
the crater of Vefuvius, and a great part of it falling, 
andxooHng on its cone; added much to the folkficy 
of the walls of this huge natural chimney, and had not 
of late years allowed of a fufficient difcharge of laVa 
to calm that fermentation, which by the ilubterra* 
fieous noifes heard at times, and by the explofions of 
fcoriseandalhes, was known to exift within die bowels 
of the volcano; fo that the eruptions of late years, 
before this laft, were fimply from the lava having 
boiled over the crater, the fides being iiifficiently 
ftrong to confine it, and oblige it to rife and over- 
flow. The mountain had been remarkably quiet 
for feveri months before the late eruption, nor did the 
^tifual fmoke ifllue from its crater, but at times it 
emitted fmall clouds of fmoke that floated in the air 
in the fhape of Httle trees. . It was remarked by 
the Father Antonio di Petrizzi, a capuchin friar 
(who printed an account of the late eruption) from 
his convent clofe to the unfortunate town of Torre 
del Greco, that for fome days preceding this erup- 
tion a thick vapour was feen to furround the n\oun« 
Itain, about a quarter of a mile beneath its crater, 
^s it was remarked by him, and others at die fame 
B b 4 timej 

376 Signs of tb4Erupti9n. [Book VI. 

time, that both the fun and the moon had often an 
vnufual reddifli caft* 

The water of the great fountain at Torre dd 
Greco began to decreafc fome da>^ before the 
eruption, fo that the wheels of a corn-nnillj work* 
. cd by that water, moved very flowly j it was ncccf- 
fary in all the other welU of thfc town and its nei^^ 
bourhood to lengthen the ropes daily, in order to 
reach at the water ; and fome of the wells became 
yquite dry. Although mod of the inhabitants were 
: fenfibleof this phenomenon, not one of them leems 
.to have fufpcftcd the true c^ufc of it. Eight days 
aMb before the eruption, a man and two boys, being 
in a .vAxcyard above: Torre del Greco (and pre^ 
cifely' oft the fpot where one of the new itiouths 
opened, whence the principal current of lava that 
cdcftroycd: the town ifiued) were much alarmed 
/by.ftiiiddcn pufF, of fmoke which ilTued from the 
earth tlofc fo them, .and was attended with a flight 
explofioaJ: ; 

:: H*d this ciroumflance, with that of the fubter^ 
raneous noifes heard at Refnia for two days before 
the eruption (with the additional one of the de- 
/creafe of water in tbi wells) been communicated at 
•the timfe,:it would have required no greac forefight 
to have been certain that an eruption of the vokano 
was. near. as hand, and that its force was direfted 
particularly towards that part of the mountain. 

On the 1 2th of June 1794* in the morning, 
there was a violent fall of rain, and foon after the 
inhabitants of Refma, fituate direftly over the an- 
cient town of Hcrculaneumi were fenfible of a 


Chap. 45.] Pncededby an EarthquiAe. 377 

rumbling fubterraneow noiie> which was not beard 
at Naples. 

From the month of January to the month of 
May, the atmofphere was generally calm, and there 
was continued dry weather. In the month of May 
there was a little rain, but the weather was unufually 
fultry. For fome days preceding the eruption, the 
Duke della Torre, a learned and ingenious 
noblcrtan, who publilh^d two letters upon the 
fubjeft of the eruption, obferved by his elec- 
trometers, that the atmofphere was charged in 
excefs with the eleftric fluid, and continued . 
fo for feveral days during the eruption. 

•About eleven o'clock on the night of the 1 2th 
of June, the inhabitants of Naples were all fenfiblc 
of a violent (hock of an earthquake $ the undula- 
tory motion was evidently from eaft to weft, and 
appeared to have lafted near half a minute. The 
(ky, which had been quite clear, was foon aftef 
covered with black clouds. The inhabitants of the 
towns and villages, which are very numerous at the 
foot of Vefuvius, felt this earthquake ftill more 
fenfibly, and fay, that the fhock at firft was from 
the bottom upwards, after whjch followed the un- 
dulation from eaft to weft. This earthquake ex- 
tended all over the Campagna Felice; and the 
royal palace at Caferta, which is fifteen miles from 
I^aples, and one of the moft magnificent and folid 
buildings in Europe (the walb bemg eighteen feet 
thick) was (hook in fuch a manner as to caufe great 
alarm, and all the chanJber bells rang. It was 


37^ • ^^rrents rfinrmng Lofva. [Book VL 

likewife much felt at Benerencum, about thbtf 
miles from j^aples; and at Ariano in Pugliiy 
whrch is at a much greater diftancc; botb cfcele 
towns> indeed^ have been often afflided with cardi- 

On Sunday the 15th of June, foon aficn ten 
o'clock at night, another fhock of an eartbqidke 
was feh at Naples, but did not appear to be quite & 
violent as that of the 12th, nor did it laft fb long; 
at the fame mdment a fountain of bright fire, at* 
tended with a very black fmoke and a loud report, 
was feen to iflbe, and rife to a great hei^t, from 
about the middle of the cone of Vefuvius 5 Ibon 
after another of the fame kind broke out at ibme 
little diftance lower down'; then, as is fuppofed by 
the blowing up of a covered channel full of red hot 
lava, it had the appearance as if the lava had taken 
its courfc direftly up the fteep cone of the volcano. 
Frelh fountains fucceeded one anothcV ha{tily> and 
all in a direct line tending, for about a mile and a 
half down, 'towards the towns of Redna and Torrt 
del Greco. Sir William Hamilton conld count 
fifteen of them, but believes there were others ob- 
Icured by the fmoke. It feems probable, that all 
thefe fountains of fire, from their being in fuch an 
exa£i: line, proceeded from one and the fame long 
fifTure down the flanks of the mountain, and that 
the lava and other volcanic matter forced its way 
II out of the wideft parts of the crack, and formed 

%i there the fittle mountains and craters that will be 

^^^. defcribed in their proper place. It is impoflible 

^t any defcription Can give an idea of this fiery 


Chap. 45.} AwfulDycbarge ofVohdnU Mailer. 379 

fcenc, or of the horrid noifcs that attended this 
great operation of nature. It was a mixture of die 
loudeft thunder, with inceflant reports, like thofe 
from a numerous heavy artillery, accompanied by 
a continued hollow murmur, like that of the roar- 
ing of the ocean during a violent ftorm ; and, add- 
ed to thefc was another blowing noife, like that of 
the afcending of a large flight of Iky-rockets, or 
that which is produced by the aftion of the enor- ' 
mous bellows on the furnace of the Carron iron 
fbundery in Scodand. The frequent falling of the 
huge ftones and fcoriae, which were thrown up to 
an incredible height from fome of the new moudis, 
and one of which having been fince meafured by 
the Abbe Tata was ten feet high, and thirty-five in 
circumference," contributed undoubtedly to the 
concuffion of the earth and air, which kipt all the 
houfes at Naples for feveral hours in a conftant 
tremor, every door and window Ihaking and rat- 
tling incedantly, and the bells ringing. This was an 
awful moment I The Iky, from a bright full moon 
and flar-light, began to be obfcured; the moon 
had prefently the appearance of being in an edipfe, 
and foon after was totally loft in obfcurity. Thci 
murmur of the prayers and lamentations of a nu- 
merous populace forming various proceflions, and 
parading in the ftreets, added to the horror. As 
the lava did not appear to have yet a Aifficient vent, 
and it was now evident that the earthquakes already 
felt had been occafioned by the air and fiery matter 
confined within the bowels of the mountain, and 


5to ' Dreadful Conflapatian. [Book VI. 

probably at no fmall depth (conCdcring the extent of 
iboie earthquakes) Sir William recommended to the 
company that, was widi him> who began to be much 
alarmed, rather to go and view the mountain at ibmc 
greater diftance, and in the open air, than to re- 
main in the houfe, which was on the fea-fide,. and 
in the part' of Naples that is neareft and nr>oft ex- 
pofed to Veliivius. They accordingly proceeded 
to Pofilipo> and viewed the conflagration, now be- 
come ftill more confiderablc, from the fca-fidc 
under that mountain ; but whether from the erup- 
tion having increafed, or from the loud reports of 
the volcanic cxploCons being repeated by the 
jnountain behind them, the noife was much louder, 
and more alarming than that they had heard in their 
firft pofition,. at leaft a mile nearer to Vefuvius, 
After fome time, and which was about two o'clock 
in the morning of the 1 6th, havbg oWcrved that 
the lavas ran in abundance, freely, and with great 
Telocity, havmg made a confiderable progrefs to- 
wards Refina, the town which it firft threatened, 
ZsA that the fiery vapours which had been confined 
bad now free vent through many parts of a crack of. 
more than a mile and a half in length, as was evi- 
dent from the quantity of inflamed matter and 
black fmoke, which continued to ifTue from the 
new mouths above mentioned, without any inter- 
luption, our author concluded that at Naples all 
danger from earthqxiakes, v which had been his 
greateft apprehenfion, was totally removed, and 
te returned to his former ftation at St, I^ucia at 


Chap. 45.3 Vclcamc. klcBritityi 3? 1 

All this time there was riot the fmallcft ap- 
pearance of fire or fmoke ffom the crater on the 
fummit of Vefuviusj but the black fmoke and allies 
ilTuing continually from fo many new mouths^ or 
craters, formed an enormous and denfe body of 
clouds over the whole mountain, and which 
began to give figns of being replete with the clec 
trie fluifl, by exhibiting flaflics of that fort of zig- 
zag lightning, which in the volcanic language of 
the country is called ferilli^ and which is the con-^ 
ftant attendant on the moft violent eruptions. 

Sir William Hamilton proceeds to remark, 
that during thirty years that he had refidcd at 
Naples, and in which fpace of time he had been wit- 
nefs « many eruptions of Vefuvius, of one fort or 
other, he never faw the cloud of fmoke replete with 
the eleftric fire, except in the two great eruptions 
of 1767, that of T779, and during this more 
formidable one. The elcftric fire, in the year 
1779, that played conftantly within the enormous 
black cloud over the crater of Vefuvius, and fel- 
dom quitted it, was exactly fimilar to that which 
is produced, on a very finall fcale, by the conductor 
of an cleftrical machine communicating with an in- 
fulated plate of glafs, thinly fpread over with me- 
tallic filings, &c. when the eledric matter continues 
to play over it in zig-zag lines without quitting it. 
He was not fcnfiblc of any noife attending that 
operation in 1779 i whereas the difcharge of the 
eledbrical matter from the volcanic clouds during 
this eruption, and particularly the fecondand third 
days, caufed cxplofions like thofc cl rne -oudcft 


^ Vdcamc Uj^tmng. [Bodk VL 

thunder K^uid indeed the ftormsraifcd evidently by 

the fole power of the volcano^ rcfemblcd in every 

refpeft all other thunder-ftorms \ the lightning fall* 

ing and deftroying every thing in ics courie. The 

houfe of the Marquis of Berio at St. Jorio^ lituatc 

at the foot of Vcfuvius, during one of thefe volcajiic 

ftorms was ibiick with lightning, which having 

ihattered many doors and windows^ and damaged 

the furniture^ left for fome time a ftrong ImcU of 

fulphur in the rooms it pafled through. Out of 

thefe gigantic and volcanic clouds, befides the 

Iightnbg> both during this eruption and that of 

1779, the author adds, he had, with many others^ 

ieea balls of fire ifllie, and fome of a confidcrable 

magnitude, which burfting in the air, produced 

nearly the fame effeft as that from the air balloons 

in fire-works, the eleftric fire that came out having 

the appearance of the ferpents with which thole 

fire-work balloons are often filled. The day od 

which Naples was in the greateft danger from the 

volcanic clouds, two fmall balls of fire, joined to-^ 

gether by a fmall link like a chain-fhot, fell clofe 

to his Cafino at Pofdipo ; they feparated> and one 

fell in the vineyard above the houfe, and the other 

in the fe?, fo clofe to it that he heard the iplalh 

in the water. The Abbe Tata, in his printed ac-^ 

.count of this eruption^ mendons an enormous ball 

of this kind which flew out of the crater of Vcfii- 

vius while he was (binding on the edge of it, and 

which burft in the air at fome diftance from the 

mountain, fopn after whiqh he heard a noife like 

5 the 

Chap. 45.] Conprndtm of$he fnhaUtants. 383 

the fall of a number of ftones, or of a heavy fliower 
of haiL During the eruption of the 15th at night, 
few of the Inhabitants of Nafdes^ from the dread of 
earthquakes, ventured to go to their beds. The 
common people were either employed in devout 
proceffions in the ftreets, or were fleeping on the 
quays and open places; the nobility and gentry, 
having caufed their horfes to be taken from their 
carriages, flept in them in tlie fquares and opeq 
places, or on the high roads juft out of the town* 
For feveral days, while the volcanic ftorms of thun- 
der and lightning lafted, the inhabitants at the foot 
of the volcano, both on the fea fide and the Somma 
fide, were often fenfible of a tremor in the earth, 
as well as of the concuOibns in the air, but at Na- 
ples only the earthquakes of the lath and 15th of 
June were diftinftly and univerfally felt: this fair 
city could not certainly have re(if):ed, had not thofe 
earthquakes been fortunately of a fhort dura- 
tion. Throughout this eruption, which continued 
in force about ten days, the fever of the mountain, 
as has been remarked in former eruptions, fhowed 
itfclf to be in fome meafurc periodical, and gene- 
rally was mofl violent at the break of day, at noon, 
and at midnight. 

About four o'clock in the morning of the i6th, 
the crater of Vefuvius began to Ihow figns of being 
open, by fbme black fmoke ifTuing out of it ; and at 
day-break another fmoke, tinged with red, ifTuing 
from an opening near the crater, but on the other 
fide of the mountain, and facing the town of Ottai- 


384 Twmcf^orre delGncodiftrcyid. [BookVL 

ano, fhcwed that a new mouth had opened dirrc 

from which a confiderable ftream of lava iffued, and 

ran with great velocity through a wood, which k 

burnt; and having run about three miles in a firw 

hours it ftoppcd before it had arrived at the vine-* 

yards and cultivated lands. The crater, and all d» 

conical part of Vefuvius, was foon involved in 

clouds and darknefs, and fo it remained for feveral 

days; but above thefe clouds, althou^ of a great 

height, frefli columns of fmoke were fcen from the 

crater, rifmg furioufly ftill higher, until the whole 

mafs remained in the ufual form of a pine-tree > 

and in that gigantic mafs of heavy clouds the &rillit 

or volcanic lightning, was frequently vifiblc, even 

in the day time. About five o'clock in the mom* 

ing of the 16th, the lava which had firft broken out 

from the feveral new mouths on the fouth fide of 

the mountain, had reached the fea, and was running 

into it, having overwhelmed, burnt, and dcftroyed 

the grcateft part of Torre del Greco, the principal 

ftream of lava haying taken its courfe through the 

very center of the town (fee plate II.) *• They 

obfcrved from Naples, that when the lava was in the 

vineyards in its way to the town, there ifllied often, 

and in different parts of it, a bright pale flame, and 

very different from the deep red of the lava; this 

"Was occafioned by the burning of the trees that 

* This view was taken from a boat on the fea near that 
town, about five in the morning of the i6th of J une, and while ■ 
the lava was ilill advancing in the Tea. The rocks, on which 
are two figures near the boat, were formed by a lava that ma 
into the fea doripg a former eniptioa of Mount Vefuvius. 


Cl^ap. 45* J ProdH3i$n tf Heater in Jbmjfhere. 385 

llipported the vines. Soon after the begioning of 
this eruption, afhes fell thick at the foot of the 
ittountain, all the way from Portici to the Torre 
del Greco I and what is remarkable, although 
there were not at that time any clouds in the air, 
except thofe of fmoke from the mountain, the afhes 
were wet, and . accompanied vrith lai^ drops of 
water, which were to the taftc very faltj the road, 
which is paved, was as wet as if there had been a 
heavy fhower of rain. ^ Thofe aihes were black and 
coarfe, like the fand of the fea-fhore, whereas thofe 
that fell there, and at Naples fbme days after, were 
of a light-grey colour, and as fine as Spanifh fnufi^ 
or powdered bark. They contained many faline 
particles ; thofe afhes that lay on the ground, ex- 
pofed to the burning fun, had a coat of the whiteft 
powder on their furface, which to the tafle was 
extremely fait and pungent. In the printed account 
of the eruption by Emanuel Scotti, dodbor of phyfic 
and profcifTor ofphilofbphy in the univerfity of 
Naples, he fuppofes (which appears to be highly 
probable) that the water which accompanied the 
fall of the afhes at the beginning of the eruption, 
•was produced by the mixture of the inflammable 
and dephlo^ftiqited air. 

By the time that the lava had reached the fea, 
between five and fix o'clock in the morning of the 
1 6th, Vcflivius was fb completely involved in 
darknefs, that the violent operation of nature that 
was going on there could no longer be difcerned, 
and fo it remained for feveral days; but the dread* 
fill noife, and the red tinge on the clouds over the 

Vol. II. C c top 

3S6 Intenfe Heat af ibe Sea fVaier. . [Book VI. 

top of the mountain^ were evident figns of the 
adivity of the fire underneath. The Uva ran 
but flowly at Torre del Greco after k had reached 
the fcaj and on the 17th of June in the morn- 
ing, its courfe was (topped, excepdng that at 
times a little rivulet of liquid fire iifued from under 
the fmoaking fcorise into the fea, and cauled a hif- 
ling noife, and a white vapour fmoke; at other 
times, a quantity of large fcorise were pufhcd off 
the furface of the body of the lava into tht fea, dis- 
covering that it was redhot under that furface ; and 
even to the latter end of Auguft the center of the 
thickeft part of the lava that covered the town re- 
tained its red heat. The breadth of the lava that 
ran into the fea, and formed a new promontory 
there, after having deftroyed the greateft part of 
the town of Torre del Greco, having been exadtly 
meafured by the duke della Torre, is of Englilh 
feet it204. Its height above the fea is twelve feet, 
and as many feet under water; fo that its whole 
height is twenty-four feetj it extends into the fea 
626 feet. The fea water was boiling as in a cauU 
dron, where ic waftied the foot of this new fonned 
promontory : and although our author was at leaft 
a hundred yards from it, obferving that the fea 
fmoked near his boat, he put his hand into the 
water, which was literally fcalded; and by this 
time his boatmen obfcrved that the pitcK from the 
bottom of the boat was m.elting fail, and floating on 
the furface of the fea, and that die boat began to 
leak; he therefore retired haftily from tlvs Ipot, and 
landed at fume diftance from the hot lava. The 


a Chap. 45.] .Temerity of certain Nuns. ^ 387 

s town of Torre del Greco contained about i8,o6o' 

1 inhabitants, all of whom (except about 15^ who' 

s from either age or infirmity could not be moved, 

I and were overwhelmed by the lava ih their houfcs) 

: efcaped either to Caftel-a-mare, which was the an- 

cient Stabiae, or to Naples; but the rapid progrefs 
of the Java was fuch> after it had altered its courle 
from Refina, which town it firil threatened, and 
had joined a frefh hva that iflued from one of the 
new moutlis in a vineyard, about a mile frond the 
town, that it ran like a torrent over the town of 
Torre del Greco, allowing the unfortunate inhabi- 
tants fcarcely time to fave riieir lives j their good^ 
and cfFefts were totally abandoned, and indeed feve- 
ral of the inhabitants, whofe houfes had been fur- 
rounded with lava while they remained in them, 
efcaped from them, and faved their lives the follow- 
ing day, by coming out of the tops of their houfes, 
and walking over the fcorise on the furface of the 
ncdhot lava. Five or fix old nuns were taken out 
of a convent in this manner, on the i6th of June, 
and carried over the hot lava; their ftupidity was 
fuch, as not to have been the leaft alarmed, or fen- 
fiblc of their danger : one of upwards of ninety 
years of age was found aftually warming herfelf at a 
point of redhot lava, which touched the window of 
her cell, and which (he laid was very comfortable ; 
and though now apprized of their danger, they were 
ftiU very unwilling to leave the convent, in which 
they had been Ihut up almoft from their infancy, 
their ideas being as limited as the fpace they inha- 
bited. Having been defired to pack up whatever 
C c 2 . they 

3»8 Bdis defrhid of their time. [Book VI. 

they had that was mod; valuable, they all loaded 
^themfelves with bifcuits and fweetmeats, and ic 
was but by accident it was difcovered that they had 
left a fum of money bel^ind them/ which was re- 
covered for them. 

The lava pafled over the center and beft part 
of the town; no part of the cathedral rem^ed 
above it^ except the upper part of a fquare brick 
tower, in which were the bells; and ic is a curious 
circumftance, that thofe bells, although they were 
neither cracked nor melted, were deprived of their 
tone as much as if they had been cracked. When 
the lava firft entered the fea, it threw up the water 
to a prodigious height; and particularly when two 
points of lava met and inclofed a pool of water, 
that water was thrown up with great violence, and 
a loud report: at this time, as well as the day after- 
alio, a great many boiled {i(h were &ta floating on 
the furfece of the fea. 

The lava over the cathedral, and in other parts 
of the town, is faid to be upwards of forty feet in 
thickneis; the general height of the lava during its 
whole courfc was about twelve feet, and in fomc 
parts not lefs than a mile in breadth. 

When Sir William Hamilton vifited it on the 
17th of June, the tops of the houfes were juft vifi- 
ble here and there in fome parts, and the timbers 
within ftill burning cauied a bright flame to iflue 
out of the furface; in other parts, the fulphur and 
falts exhaled in a white fmoke from the lava, form- 
ing a white or yellow cruft ovi the fcorise round the 
ipots where it iffued with the greateft force. He often 
6 ^ heard 

Chap, 45.] Infiance of 'Temerity^ 389 

heard Kttlc cxplofions, and faw that they blew up, 
like little mines, fragments of the fcorise and afhes 
into the air; thefe he fuppofes to have been occa« 
fioned either by rarefied air in confined cellars, or, 
perhaps, by fmall portions of gunpowder taking fire, 
as few in that country are without a gun and fomc 
little portion of gunpowder in their houfes. As the 
church feafts there are ufually attended with fire- 
works and crackers, a firework-maker of the town 
had a very great quantity of fireworks ready made 
for an approaching feaft, and fome gunpowder, all 
of whicli had been (hut up in his houfe by the lava, 
a part of which had even entered one of the rooms j 
yet he aftually faved all his fireworks and gunpow- 
der fome days after, by carrying them fafely over 
the fcorias of the lava, that was redhot underneath. 
The heat in the ftreets of the town, at this time, 
was fo great as to raife the thermometer to very 
near one hundred degrees, and clofe to the hot lava 
it rofe much higher. Sir Wiilliam remarked in 
his way home, that there was a much greater 
quantity of the petroleum floating on the furface of 
the fea, and diffufing a very ftrong and offenfivc 
fmell, than was ufual; for at all times in calms, 
patches of this bituminous oil are to be feen float* 
ing on the furface of the fea between Portici and 
Naples,, and particularly oppofite H village called 
Pietra Bianca. The minute afhes continued falling 
at Naples; and the mountain, totally obfcured by 
them, continued to alarm the inhabitants with re- 
peated loud explofions« 

C c 3 Oa 

390 Immenje Volume of Vapour. [Book VI. 

On Wcdnefday June iS^ the wind having for i 
Ihort fpacc of time cleared away the thick cloud 
from the top of Vcfuvius, it was now di(covered 
that a great part of its crater, particularly on the 
weft fide oppoGte Naples, had fallen in, which ic 
probably did about four o'clock in the morning of^ as a violent fliock of an earthqiiake W9$ 
felt at that moment at Refina, and other paity 
fituate at the foot of the volcano. The doyds ff * 
fmoke^ mixed with the a(hes, were of fuch a 
^ to appear to have the greateft difficulty in 
their paflage out of the now widely c: 
mouth of Vefuvius, which certainly, fince the 
fell in, canpot be much fhort of two miles in citr 
cumference. One cloud heaped on anotherj aid ' 
focceeding one another incelTandy, formed in |i 
few hours fuch a gigantic and elevated coluniiilil : 
the darkeft hue over the moyntain, as UttxBmk. 
to threaten Naples with immediate defti 
having at one time been bent over the ciqr^ 
appearing to be much too maflivc and 
to remain long fufpended in the ^\x\ it 
fides, repletf with the ftriUi, or volcanic ligl 
which was ftronger than common lij^i 
juft as Pliny the younger dcfcribes it in 
his letters to Tacitus, when he fays fu 
ilU etjimiki et mtgarcs trant*. (Sec plate III .J; 


* This view was taken from Naples, and gives a very pat 
idea of the appearance of Mount Vefuvius, like a moleJuU, a| 
comparifon of the enormous mafs that hung over it, — ^The VbA 
Ijnes ihow the form of the top of Vcfuvius, as it was before tUl 
enxption^ and when the crater was only the width of the vpper 


.'y.fu 3 

Chap. 45.] Torrents of Mud. 391 

Vefuvius was at this time completely covered, 
as were all the old black lavas, with a thick coat of 
thofe fine light-grey afhes already fallen, which 
gave it a cold and horrid appearance; and in com- 
parifon of the abovementioned enormous mafs of 
clouds, which certainly, however it may contradict 
our idea of the extenfion of our atmofphere, rofc 
many miles above the mountain, it appeared like a 
molehill, although the perpendicular height of 
Vefuvius, from the level of the fea, is more than 
three thoufand fix hundred feet. The abbe Brac- 
cini, as appears in his printed account of the eriip^ 
tion of Mount Vefuvius in 163T, meafured with 
a quadrant the elevation of a mafs of clouds of the 
lame nature, 'that was formed over Vefuvius during 
that great eruption, and found it to exceed thirty 
miles in height. Dr. Scotti, in his printed account 
of this eruption; fays, that the height of this threat- 
ning cloud of fmoke and afiies, meafured from 
Naples, was found to be of an elevation of thirty 
degrees. ' 

The ftorms of thunder and lightning, attended at 
times with heavy falls of rain and afhes, caufing 
.the moft deftruftive torrents of water and glutinous 
mud, mixed with huge ftones, and trees torn up by 
the roots, continued more or lefs to afflidl the in« 
habitants on both fides of the volcano until the 
7th of July, when the laft torrent dcftroyed many 
hundred acres of cultivated land, between the towns 

line. On the fide of the mountain is reprefented the ipot 
whence the lava firll ifTued on the 15th of Juqg» wi(h its courfe 
to Torre del Greco and the fea. 

Cc4 of 

392 ^orreitis tf Mud. [Book VI. 


of Torre del Greco and Torre ddl' Aiinunziata. 
Some of thefe corrents> both on the fea fide and the 
Somma fide of the mountaioy came down with a 
horrid rufiiing noife; and fome of thenn> after hair- 
ing forced their way through the narrow guUies of 
the mountain,' rofe to the height of naore than 
twenty feet, and were near half a mile in extent. 
The mud, of which the torrents were compofed, 
being a kind of natural mortar, completely calcd 
up and ruined fome thoufand acres of rich Wne- 
yards; for it foon becomes io hard, that nothing 
leis than a pickaxe can break it up. 

The laudable curiofity of our author induced 
him to go upon Mount Vefuvius, as (bon as it was 
confiftent with any degree of prudence, which was 
not until the 30th of June, ai)d even then it was 
attended with fome rifk. The crater of Vefuvius, 
except at (hort intervals, had been continually ob- 
fcured by the volcanic clouds from the i6th, and 
was fo on that day, with frequent flafhes of light- 
ning playing in thofe clouds, and attended as ufual 
with a noife like thunder; and the fine aihes were 
Hill falling on Vefuvius, but ftill more on the moun- 
tain of Somma. Sir William went up the ufual 
way by Refina, and obferved, in his way through 
that village, that many of the flones of the pave- 
ment had been loofened, and were deranged i^ the 
cardiquakes, particularly by that of the i8th, which 
attended the falling in of the crater of the volcano, 
and which had been (b violent as to throw many 
people down, and obliged all the inhabitants of 
Refina to quit their hoxifes haftily, to which they 


Chap. 45.] Ituined State of the Country. 39J 

did not dare return for two days. The leaves of 
all the vines were burnt by the alhes that had faUen 
on them> and many of the vines themfelves wcit 
buried under the afhes^ and great branches of the 
trees that fupported them had been torn oflF bf 
their weight. In fhort^ nothing but ruin and delo- 
lation was to be feeh. The a(hes at the foot of the' 
mountain were about tea or twelve inches thick on 
the furface of the earth, but in proportion as he 
afcended, their thicknefs increafed to feveraifeei^ 
not lefs than nine or ten in fome parts j fo that the ' . 
furface of the old rugged lavas^ that before was 
almoft impraftkable, was now become a perfeft 
plain, over which he Walked with the , greateft 
cafe. The afhes were of a light-grey colour, and 
exceedingly fine, fo that by the footfteps being 
marked on them as on fnow, he learnt th«'it tltree 
fmaU parties had been up before him. He fav 
likewife the track of a fox, which appeared to have 
been quite bewildered, to judge from the many 
turns he had made. Even the traces of lizards and 
other litde animals, and of infe6ts^ were vifible on 
thefe fine afhes. Sir William and his companion 
afcended to the fpot whence the lava of the i5di 
firfl: ifTued, and followed the courfe of it, which 
was flill very hot (although covered with fuch a. 
thick coat of alhes) quite down to the fea at Tonr 
del Greco, which is more than five miles. It was 
not polTiblc to get up to the great crater of Vcfu- 
vius, nor had any one yet attempted it* The horrid 
fhafms that cxiftcd from the fpot. where the late 
fruJJtioq firft took place, in a Itrait line for near 


394 New formed Mount anu. [Book VI. 

two miles toward the fca, cannot be imagined. 
They formed vallics more than two hundred 
feet deep, and from half a mile to a mile wide; 
and where the fountains of fiery matter cxiftcd 
during the eruption, were Kttle mountains 'wirii 
deep craters. Ten thoufand men, in as many 
years, could not make fuch an alteration on the 
face of Vefuvius. Except the exhalations of ful- 
phureous and vitriolic vapours, which broke out 
from different fpots of the line abovcmcntioncd, 
and tinged the furface of the afhes and fcorise in 
thofe parts with either a deep or pale- yellow, widi 
a rcddifti ochre colour, or a bright white, and in 
fomc parts with a deep green and azure blue (fo 
that the whole together had the effed of an iris) dH 
had the appearance of a fandy defart. Our adven- 
turers then went on the top of feven of the moft 
confiderable of the new-formed mountains, and 
looked into their craters, which on fome of them 
appeared to belittle fhort of half a mile in circum 
ferenccj and although the exterior perpendicular 
height of any of them did not exceed two hundred 
feet, the depth of their inverted cone within was 
three times as great. It would not have been 
poffible to have breathed on thefe new mountains near 
their craters, if they had not taken the precaution 
of tying a doubled handkerchief over their mouths 
and noftrils; and even with that precaution they 
could not refift lorig, the fumes of the vitriolic acid 
were fo exceedingly penetrating, and of fuch a fuf- 
focating quality. They found in one a d^bfe 
crater, like two funnels joined together s and in all 


Chap. 45»'] Volcanic Whirlwinds. 395 

there was fome little fmokc and depofitions of falts 
and fulphurs, of the various colours abovemen* 
tioncd, juft as is commonly fcen adhering to the 
inner walls of the principal crater of Vcfpvius. 

Two or three days after they had been there, . 
one of the new mouths, into which they had looked, 
fuddenly nhade a great explofion of ft6nes, fmoke, 
and afhes, which would certainly have proved fatal 
to any one who might unfortunately have been cherc 
at the time of the explofion. We rc;d of a like 
accident having proved fatal to more than twenty 
people, who had the curiofity to look into the cra- 
ter of the Monte Nuovo, near Pozzuoli, a few 
days after its formation, in the year' 1538. The 
15th of Auguft, Sir William faw a fuddcn explo- 
fion of fmoke and aflics thrown to an extreme 
height out of the great crater of Vefuvius, that mufl: ^ 
have dcftroyed any one within half a mile of it ; . 
and yet on the 1 9th of July a party not only had 
vifited that crater, but had defcended 170 feet 
* within it. While they were on the mountain, two 
whirlwinds, exaftly like thofe that form water-fpout% 
at fea, made their appearance j and one of them, 
whi;:h was very near, made a ftrange rulhing nolle, 
and having taken up a great quantity of the fine 
albes, formed them into an elevated fpiral column, 
which, with a whirling motion and great rapidity, 
was carried toward the mountain of Somma, where 
it broke and was difperfed. One of oUr author's 
fervants, employed in collecting of fulphur, or lal 
ammoniac, which cryftallizcs near the fumaroli, as 
(bey arp called (and which are the fpots whence the 


396 N€w formed Craters. £Bo<Jc VI 

hot vapour iflues out of the frefh lavas) fbuod^ to hk 
great furprize^ an exceeding cold wind ifTue froin a 
fiiliire very near the hot fiimaroli upon his leg. Ir 
a vineyard not in the fame line with the new-fbrnied 
mountains juft defcribed, but in a right line froni 
them> at the diftance of little more than a mile from 
Torre del Greco, they found three or four more of 
thefe new-formed mountains with craters^ out of 
which the lava flowed, and by uniting with the 
ftreams that came from the higher mouths, and 
adding to their heat and fluidity, enabled the whole 
current to make fo rapid a progrefs over the unfbr* 
tunate town, as fcarcely to allow its inhabitants fuf^ 
ficient time to efcape with their lives. The rich 
vineyards belonging to the Torre del Greco, and 
which produced the wine called Lacrima Chriftit 
that have been buried, and are totally deftroyed hj 
this lava, confided of more than three thouiand 
acres i but the deftruftion of the vineyards by the 
torrents of mud and water, at the foot of the moun- 
tain of Somma, was much more extenfivc. 

In that part of the country, the firft figns of a 
torrent that our author met with, was near the vil- 
lage of the Madonna dell' Arco, and he pafled ieve- 
rai others between that and the town of Ottaiano; 
one near Trochiajj and two near the town of Som- 
ina> were the moft confiderable, and not lefs than a 
quarter of a mile in breadth j and, according to 
^e teftimony of eye-witneflTes, when they poured 
down from the mountain of Somma, they 'were 
from twenty to thirty feet high; the matter of thcfc 
torrents was a; liquid glutinous mud^ compofedof 


chap. 45.] Immenfe fatuity of Ajbes. 397 

fcorix, a(hes, ftones (fome of ah enormous (ize) 
mixed with trees that had been torn up by the roots. 
Such torrents, as it may well .be imagined, were 
irrefiftible, and carried all before them; houfes, 
walls, trees, and not lefs than four thoufand Iheep 
and other cattle. At Somma, a team of eight oxen, 
which were drawing a large timber tree, were at 
once carried off, and never were heard of more. 

The appearance of thefe torrents was like that 
of all other torrents in mountainous countries, ex- 
cept that what had been mud was become a perfedb 
cement, on which nothing lefs than a pickaxe could 
make any impreffion. The vineyards and culti- 
vated lands were here much more ruined ; and the 
limbs of the trees much more torn by the weight of 
the afhes, than thofe which have been already dc- 
fcribed on the fea fide of the volcano. 

The abbe Tata, in his printed account of this 
eruption, has given a good idea of the abundance^ 
the great weight, and glutinous quality of thefe afhes^ 
when he fays, that having taken a branch from a fig« 
tree flill flanding neat the town of Somma, on 
which were only fix leaves, and two little unripe 
figs, and having weighed it with the afhes attached 
to it, he found it to be thirty-one ounces; when 
having wafhed off the volcanic matter, it fcarcely 
weighed three. 

In the town of Somma, our author found four 
churches and about feventy houfes without roofs, 
and full of afhes. The great damage on that fide 
of the mountab, by the fall of the afhes and the tor- 
rents, happened on the i8tb, i9ch> andaothof 


39* Ohfenaticnj en the Great Crater. [Book VI, 

June, and on the 12th of July. The 19th, die 
afhes fell fo thick at Somma, that unlefi a pcdbn 
kq)t in mction, he was foon fixed to die ground bf 
rhem. This fall of afhes was accompanied alio 
with loud reports, and frequent flafhes of the volca- 
nic lightning, fo that, furrounded by fo niany hor- 
rors, it was impoffible for the inhabitants to remain 
in the town, and they all fled; the darknefs was fuch> 
^ although it was mid-day, that even with the help of 
torches it was fcarcely pofTible to keep in the high 
road. On the i6th of July, fignor Guilcppe Sacco 
went up to the crater, and, according to his account 
which has been printed at Naples, the crater is of 
an irregular oval form, and, as he fuppoies (not 
having been able to meafure it) of about a mile 
and a half in circumference \ the infide, as ufual, in 
the fhapc of an inverted cone, the inner walls of 
which on the eaftern fide are perpendicular; but on 
the weftern fide of the crater, which is much lower, 
the defcent was practicable, and Sacco with fbme 
of his companions adually went down one hundred 
and feventy-fix palms, from which Ipot, having 
lowered a cord with a ftone tied to it, they found 
the whole depth of the crater to be about five hun- 
dred palms. But fuch obfervations on the crater 
of Vefuvius are of little confequence, as both its 
form and apparent depth are fubjeft to great alte- 
rations from day to day. 

The 2 ad of July, one of the new craters, 
which is the neareft to the town of Torre del Greco, 
threw up both fire and fmoke, which circumflance, 
added to that of the lava*s retaining its heat much 


[^' Chap. 45.] Supernatural Darknefs. 39 j 

1 longer than ufual, fecmcd to indicate that there was 
ii: ftill fomc fermentation under that part of the vol- 
E cano. The lava in cooling often cracks> and caufes 
a a loud explofion, juft as the ice does in the glaciers 

2 in Swifferland j fuch reports were frequendy heard 
sr at this time at the Torre del Greco ; and a vapour 
•: was often feen to ifliie from the body of the lava, 
t and taking fire in air, fall like thofe meteors vulgarly 
I called falling ftars. 

: The darknefs occafioncd by the fall of the afhes 

J ' in the Campagna Felice extended itfelf, apd varied, 

t according to the pi-evailing winds, Dn the 19th of 

: • June it was fo dark at Caferta, which is fifteen 

B miles from Naples, as to oblige the inhabitants to 

light candles at mid-day ; and one day, during the 

^ eruption, the darknefs fpread over Beneventum, 

I which is thirty miles from Vefuvius. 

; The archbiihop of Taranto, in a letter to Naples, 

J and dated from that city the 1 8 th of June, obferves, 

f We are involved in a thick cloud of minute vol- 

( canic afhes, and we imagine that there mult be a 

1 great eruption either of Mount Etna, or of Strom- 

, boli/ The biftiop did not dream of their having 

proceeded from Vefuvius, which is about t^o hun-' 

dred and fifty miles from Taranto. Afhes alfo fell, 

during the late etuption, at the very extremity of the 

province of Lecce, which is ftill farther off; at Mar* 

tino, near Taranto, a houfe was ftruck and much 

damaged by the lightning from one of the clouds. 

In the accounts of the great eruption of Vefuvius in 

163 1, mention is made of the extenfive progrels of 

the aftics from Veiuvius, and of the damage done 


40O Curious Phenomena at SUuna. [Boole Vf. 

hf the ferilli, or volcanic lightnings which attended 
thenn in their courie. 

Our author in this place mentions a very extra- 
ordinary circumftancc, which happened near Sienna, 
on the Tufcan ftate, about eighteen hours after the 
commencement of the late eruption of Vcfuvius on 
the 15th of June, although he adds, that phenome- 
non milfl have no relation to the eruption ; it was 
communicated to him in the following words by 
the earl of Briftol, biftiop of Dcrry> in a letter dated 
I from Sienna, July la, i794- * In the midft of a 

\ mod violent thunder-ftorai, about a dozen ftones of 

I various weights and dimenfions fell at the feet of 

t different people, men, women, and children ; the 

I ftones are of a quality not found in any part of the 

Siennefe territory ; they fell about eighteen hours 
after the enormous eruption of Vcfuvius, which 
circumftancc leaves a choice of difficulties in the 
(blution of this extraordinary pha:nomenon: either 
thefe ftones have been generated in this igneous 
! mafs of clouds, which produced fuch unufual thun- 

i der, or, which is equally incredible, they were 

thrown from Vefuvius at a diftancc of at leaft two 
hundred and fifty miles i judge then of its parabola.' 
One of the largeft ftones, when entire, weighed 
upwards of five pounds. The outfide of every 
ftone that was found, and afcertained to have faUen 
from the cloud near Sienna, was evidently frclhly 
vitrified, and black, having every fign of having paf- 
fed through an extreme heat; when broken, the 
infidc was found of a light-grey colour mixed with 
' black 

Chap, 4^.] Cbudshifraffediy'ibe Volcano. '/fi>% 

black ipotSj and fome (hining particles, fuppbfed to 
be pyrites. Stones of th6 feme nature, at'leaft a^ 
far as the eye can judge 6f them, are 'frequently 
found on Mount VefuviuB; and- fbould Omilar 
ftones be . found, •with the fame ^vitrified coat on 
them, on Mount Yefiivius, the queftibn' would be 
decided 4nfevour of Vefuvius, unlefs'ir could be 
proved that thcnc'-hari been, abourthe tin:je of th*. 
fall of^thcfc ftOTcs. in - the Sancfe territory, fome 
nearer opening of the earth, attended ^ith an emit 
fion of volcanic matter, which might very well hap- 
peny as the mountain of iRadicofani, within fifty 
miles of Sienna, is certainly volcanic. The cele- 
brated fcither Ambrogio Soldani, profeflbr of ma- 
thematics in the univerfity of Sienna, is printing 
there his differtation upon this extraordinary phaeno- 
roenon; wherein, it is faid, he has decided that 
thofe ftones were generated in the air independently 
of volcanic afliftance. 

Until after the yth of July, when the laft cloud 
broke over Vefuvius, and fornried a tremendous 
torrent of mud^ which took its courfe acrols the great 
road between Torre del Greco and the Torre dell* 
Annunziata,'and deftroyed many vineyards, the late 
eruption*could not be faid to have finifhed, although 
the force of it was over the dad of June. The 
power of attraction in mountains is well known; 
but whether the attraftivc power of a volcanic 
mountain is greater than that of any other moun- 
tain, is a queftion. During this laft eruption^ how- 
ever, it apjiearcd that every watery cloud was evi- 
dently attrafted by Vefuvius, and the fuddcn diflb- 

VoL, II. D d lution 

4^9 J^hfkitlc Vatmtn [Book VL 

lution of thofe clouds left marks of tbdr ddftni^Uve 
power on the faije of the country all round the baBs 
of the vot<^ano. Since the mouth of Vefuvius was 
enlarged) our author (ays he has ieen a great cloud 
pafling over it, and which not 00I7 was attra&edj 
$Qt was focked in> and diiappeared in a moment. 
. After every violent erupdon of Mount Vefu- 
vius^ we read of damage done by a xnephitic va« 
pourj which coming from imder Ae ancient lavas, 
infinuates itfelf into low places, fiich as the cellan 
and wells of the houfes fituate at the foot of tbe 
volcano. ; After the eruption of 1767, there were 
feveral inftances, as in this, of people going into 
their cellars at Portid, and other parts of that neigh- 
bourhood, having been ftruck down by this va- 
pour, and who would have expired if they had not 
been haftily removed. Thefe occafional vapoursi 
vm^ef^9 are of the fame quality as that permanent 
one in the Grotta del Cane, near the lake of 
AgnanOj and which has been proved to be chiefly 
fixed air. The vapours, that in the volcanic lan- 
guage of Naples, are cdSic^d fumaroli^ are of another 
nature, and iffiie from fpots aU over the frefti and 
hot lavas while they arc cooling 5 they arc iulphu- 
rcous and fuffbcating, fo much fo, that often the 
birds which arc flying over them arc ovcrpowerteJ, 
and fall down dead. Thefe vapours depoGt a cruft 
of fulphur, or falts, particularly of fal ammoniac, on 
thie. fcoriae of the lava through which they pafi ; 
and the imall cryltals of which they are compoled 
are often tinged with deep or pale yellow, with a 
bright red like cinnabar, ahdfbmatimes with green, 


Chaip»450 producid fy H^ V^iiMf^ 49| 

or, an azure bliie. After the late empdgn, tnaaf 
pieces of the fcorks of the fi^fli lava were found 
powdejfed with a luckl fubftancej exactly like the 
brighteft fteel or iron filings. 

The firft appearance of the mofete, after the 
late eruption, was on the 17 th of JuiM^ when a 
peafant going with an a& to his vinefard, a little^ 
above the village of Refina, in a narrow hollow 
i^ay* the a(s dropped down, and feemed to be ex**, 
piringi the peafknt was foon fenfible of the me**; 
phitic vapour himlelf, and well knowing its fatal 
effeds, dragged the aninial out of its influtsnce^ 
and it loon recovered. This heavy vapour, when 
expoied to the open air, does not rife niuch more, 
than a foot above the fur&ce of the earth, but when 
it gets into a confined pkce, like a ceHar or well^ ic 
ri&s and fiUs as any other fiuid woukl do ; havii^ 
filled a well, it rifes above it about a fooc high, ^nd 
then bending over, falls ta the earthy on which it 
ipreads, idways preferving its ufual level* Where- 
ever this vapour iifoes, a wavering in the air jji per<« 
ceptible, like that wiiich is produced by the burning 
of charcoal; and idien it iilues from a fiflbre near 
any plants or vegetables, the leaves of thofe plants- 
are feen to move, as if they were agitated by at 
gentle wind. It is extraordinary, thac . aich^gh 
there does not appear to be any poiibnous qualiiy 
in this vapour, which in every i*elpe£t refembles 
fixed air, ic fhould prove fo very i^al to ^ ylne- 
yards, fome thoufand acres of which were deftroyed 
by it after the late erupt'ioix: when it .penetrates 
to the roots of the vines, it dries them* up, and killa 
Dd 2 the 

404^ AHiffials kiBedl^ Mifste. [BookVf> 

the plant. A pcafant m the neighbourhood of 
Rcfina, having fuffercd by the mofctc, which dc- 
ftfoycdhis vineyards in the year 1767, and having 
obfervcd then that the vapour followed the laws c^ 
all fluids; nnade a narrow deep ditch all round his 
vineyMxl, whidi communicated widi ancient lavas, 
and alfo with a deep cavern under one of them ; the 
confequence of his weU reafoncd operation wasj thac 

. slithough - furrounded by thefe noxious vapours, 
whith lay conftandy at the bottom of his ditch, 
tiiey never entered his vineyard, and hjs vines were 
in a flouri(H?rig ftate, while thofe of his neighbours 
wcre'pcnffiing. Upwards of thirteen hundred hairs, 
OTd many pheafarite and partridges, overtaken by 
this vapour,' were* found dead within his Sicilian 
majeRy's referved chafes in the neighbourhood of 
VefUvius; and alfo many domeftic cats, who in 

. tlidr purfuit after this game fell vidtims to the ukk 
fete. A ihoal of filh, of fcveral hundred weighs 
having been obfervcd by fome fifliermen at Refina 
in great agitati(m on the &irface o^ the fea> near 
fbme rocks of an ancient lava that had run into the 
fea, they furrounded them with their nets, and took 
diem all with eafe, and afterwards difcovered that 
they bad been ftunned by the mephitic vapour, 
which at that rime iflbed forcibly from underneath 
the ancient lava into the fea. 

The account t>f Sir William Hamilton is con- 
chicled by two remarks, which as they are cuiious 
I lhdrinfc!t>— 

1. Wkbiri a mile of Caftel- a-mare, the moiete 
were ftilLYery a<ftive (on Sept. a.) and particu- 

Chapf, 45.] Death of tbe-eldk P%# 40^ 

larly under the Ipot where the ancient town of 
Stabia was fituated. The a4th of Auguft, a young 
lad by accident Tailing into a well there that was 
dry, but full of the mephitic vapour, was imme- 
diately fufFocated s there were no jfigns of any injury 
from the fall, as the well was fliallow. This cir* 
cumftance called to cur author's mind the death of 
the elder Pliny, who mod pi'obably loft his life by 
(he fame fort of nriephiric vapours, on this very 
ipot, and which are aftivc after great eruptions of 

2. Mr. Jsmes, a Britifh merchant, aflured our 
author, that on Tuefday night, the 17th of June, 
which was the third day of the eruption of Mount 
Vefuvius, he was in a boat with a fail, near Torre 
del Greco, when the minute alhes, fo often mea- 
tioned, fell thick ; and that in the dark they emit- 
ted a pale light like pholphorus, fo that his hat, 
thofe of the boatmen, and the part of the fails that 
were covered with alhes, were luminous. Others 
have mentioned the having feen a phofphoric light 
on Vefuvius after this eruption; but until it was 
confirmed to him by Mr. James, he did not chufo 
fo fay any thing about it **.'* 

f Sec Phil. Tranf. for 1795, p. 73, fte. 

pd3 Crap; 

Chap. XLVL 

E A & T H aU AK E & 

Cotnuffhn ht^etn Marthquakts and Vdcanots^^^Earikqu^i 
amfid fy the Prognfi if Steam ktween the Strata of ibe 
Martk.^^SigMf of apfPMKhing Barikquakes.^m^GruU Earti* 
f9$ke at iijhtf, im ijfS.^Marttf talis m CaUAria» im 

THE fuddcn explofians whidi take place from 
volcanoes^ probably dq)end on the accefs of 
% quaatky of Wtcr» which enters through fome 
i^ure conununicacing with the fea, or which is de- 
rived from other fources in the earth. If this mafi 
of water is fufficiently great, it will extinguiih the 
volcano ; if not, it will be converted into fteam, the 
expanfive force of which &r exceeds that of gun- 
powder. The elaftic fluid, thus formed, either finds 
vent at the mowh of the volcano, or, if the fuper- 
igicumbent weight fhould be too great, it will force 
a p^ge between the (hata of the earthf and oeca- 
(ion that undulatory but ibmetimes violent mociQa 
which is called an earthquake^ From various 
h&.% demoni^rative of the cohefion and elafticity 
of bodies, we are warranted in concluding, that the 
different ftrata of which the earth is compofed wiU 
adhere together^ and that a freer paflTage will be 
afforded to any intervening body between the 
ftrata than direftly through them. If the confined 
fire afts dircftly under a province or town^ it will 


ChsLp.^6J] Coij/e of Earfiquahs. J^j 

heave the earth perpendicularly upwards, and the 
ihocks will be more fudden and violent. If it a£^s 
at a diftance, it will raUe that traft obliquely, and 
the motion will be more oblique^ undulatory, add 

The great earthquake atLifbon, in 1755, was 
felt as far as Scotland, and from the phenomenia 
which attended it, it was evident^ that the ground 
' had a waving modon from fouth to north. All the 
oblong lakes, that lay from north to fouth, were 
much agitated, the wave commencing at the fouth 
end, whilft all other lakes which lay acrofs, from 
caft to weft, were much lefs affefted. 

The great diftance to which earthquakes extend 
depends on the conhpreffibility and elafticity of the 
earth, which may be undcrftood from the vibra- 
tion of the walls of houfes, occafioned by the paff- 
ing of carriages in the adjacent ftreets. Another 
inftance is the vibration of fteeples by the ringing of 
bells or gufts of wind. The Eddiftone lighthoufe 
often vibrates from the force of the waves which 
beac againft its foundation. 

Previous to an eruption of Vefuvius the earth 
always trembles, and fubterraneous explofions arc 
heard. On the ift of November, 17551 the era fo 
fatal to Lifbon, the ifland of Madeifa was violently 
Ihaken by an earthquake, accompanied with fub* 
terraneous explofions. So thoroughly convinced, in- 
deed, are the inhabitants of volcanic courttries of the 
connexion between earthquakes and volcanoes, that 
when a grtjjt eruption takes pla«e from a volcano, 
P d 4. • - they 

4o8 Cauje of Earthquakes. [Book VI, 

they congratulate themfelves on. having elcapc^l a« 

Earthquakes as well as volcanic eruptions are at» 
•ways preceded by a violent agitation of die fei* 
Previous to xhc breaking out of Vefuvius, the fca 
retires from the adjacent fhores till the mountain is 
burft open, and then it returns with fuch impetu- 
ofity as to overflow its ufual boundary. About an 
hour after the firft Ihocks, which alarmed the city 
of Lifbon in 1755, the fea was obferved to come 
rulhing towards the city like a torrent, though 
againft both wind and tide ; it rofe forty feet 
higher than was ever known, and z,h fuddenly fub- 
fided. A fhip, fifty leagues off at fea, received (o 
violent a fliock as greatly to injure the deck, &c. 
The fame efFcdt was obferved at Cadiz, and at a 
variety of ports throughout the Mediterranean, and, 
indeed, more or Icfs, all over Europe. 

That earthquakes are the cfFeft of fteam gene- 
rated within the bowels of the earth, and that they 
are produced in the manner which has been defcrib- 
cd, appears highly probable from the quantities of 
fteam and boiling water which have occaOonally 
been thrown up by volcanoes in different parts of 
the world. An 163 1 and 1698 vaft torrents of 
boiling water flowed from the crater of Vefuvius, 
previous to the eruption of fire : and what was, 
perhaps, ftill more remarkable, many fpecies of 
fea-fhells, in . a calcined ftate, were found on the ' 
brink of the crater, and alfo in the channel formed 
by the flood. The fame thing happened at JEtna, 
"^ *755* when a dreadful torrent of boiling water 


Chap- 46.] Earthquake at lijben. 40^ 

flowed from the crater at the time of ah eruption of 
fire. Sir William Hamilton obferves, that the fca- 
ihcUs emitted along with the water dearly indicate 
m communication with the fea. All warm fprings 
probably receive their heat from the aftion of py- 
rites, near which the water pafies. 
• The following .account of the great Lifbon 
earthquake is extrafted from a volume of letters, 
publiflied a few years ago by the reverend Mr, 
Davy : 

* There never was a finer morning feen than the 
firft of November ( 1755) 5 the ^^^ flione out in its 
full luftre J the whole face of the (ky was ptrfeftly 
fcrcne and clear, and not the leaft fignal or warn- 
ing of that approaching event, which has made this 
once flourifliing, opulent, and populous city, a fcene 
of the utmoft horror and defolation, except only 
fuch as ferved to alarm, but fcarcely left a mo- 
ment's time to fly fi^m the general deftruftion. 

* It was on the morning of this fatal day, be* ' 
tween the hours of nine and ten, that I was fat down 
in my apartment, juft finifhing a letter, when the 
papers and table I was writing on began to tremble 
with a gentle motion, whish rather furprized me, 
as I could not perceive a breath of wind ftirring; 
-whilft I was rcflefting with myfelf what this could 
be owing to, but without having the leaft apprc- 
henfion of tljie real caufe, the whole houfc began 
to (hake from the very foundation, which at firft I 
imputed to the rattling oi feveral coaches in the 
main ftreet, which ufually paffed that way, at this 
time, from Belem to die palace ^ but on hearken* 


416 Gfiat Earthquake [Boc^ VI. 

ing more attentively, I was loon undeceived, as I 
foand it was owing to a ftrange frightful kind of 
noife under ground, refcmbling the hollow diflant 
rumbling of thunder ; all tliis pafied in lels than a 
a minute, and I muft confefs I now began to be 
alarmed, as it naturally occurred to me, chat this 
noifc might poffibly be the forerunner of an earth- 
quake, as one I remembered, which had happened 
about fix or feven years ago, in the Ifland of' Ma- 
deira, commenced in the fame manner, though it 
did little or no damage. ^ 

* Upon this I threw d*wn my pen, and flarted 
upon my (ttu remaining a moment in fuipenfc, 
whether I (hould ftay in the apartnnent, or run 
into the ftreet, as the danger in both places feemed 
equal] and ftill flattering my felf that this tremor 
might produce no odicr effefts than fuch inconfi- 
derable ones as had been felt at Madeira i but in a 
moment I was roufed from my dream, being inftandy 
fhinned with a moft horrid cralh, as if every edifice 
in the city had tumbled down at once. The houfe I 
was in fhook with fuch violence, that the upper 
ftorics immediately fell, and though my apartment 
(which was the firft floor) did not then fliarc the 
fame fate, yet every thing was thrown out of its 
place in fuch a manner, that it was with no fnaall 
di/Ecuky I kept, my feet, and expe^<fd nothing kls 
than to be foon cruflied to death, as the walls con- 
tinued rocking to and fro in the frightfulleft man* 
ner, opening in fcvcral places, large ftoncs fall- 
ing dow|i on every fide from the cracks, and the 
ends of moft of the rafters Rating out from the roof, 


Chap. 46-1 afUJbtm. 4" 

To add to this terrifying fcene, the flcy in a mo^ 
mcnt became fo gloomy^ that I could now 'diftin* 
guifh no particdar objeftj it was an £gyptiail 
darkneis indeed^ fuch as might be felt; owing, no 
doubt, to the prodigious clouds of duft and lirne^ 
raifed from fo violent a concuffion, and as fome 
reported, to fulphureous exhalations, but this I can- 
not affirm ; however, it is certain I found myfelf 
almoft choakcd for near ten minutes. 

* As foon as the gloom began to difperfe, and the 
violence of the fhock feemed pretty much abated, 
the firft objeft I perceived in the room was a wonlian 
fitting on the floor, with an infant in her aroM, all 
covered with duft, pale and trembling i I ^ed her 
Jiow (he got hither : but her confternatrbn was fo 
great that Ihe could give me no account of her 
efeape j I iuppofe, that when the tremor firft began, 
ihe r^n out of her own houfe, and finding herfeUf in 
fuch imminent danger from the falling of ftones, re* 
tired into the door of mine, which was almoft con- 
tiguous to her's, for Iheltcr, and when the jhock 
increafcd, which filled the door with duft and rub- 
bift), ran up ftairs into nny apartment, which was 
then open : be it as it might, this was no time for 
eurioficy. I remember the poor creature afked 
me, in the utmoft agony, if I did iiot think that the 
world was at an end ; at the fame time Ihe complain- 
ed c^ being eboaked^ and begged for God^s fake 
I would procure her a little drink; upon this I went 
to a ck>fet where I kept a large jar with water (which 
you know is fometimes a pretty fcarcc con)modity 
in Liibon) but finding it broken in pieces, I told her 



4 w Great Earthquake £Book VI, 

ihc muft not now think of quenching hcrthirft, but 
faving her life, as the houfe was juft falling on our 
heads, and if a fecond fhock came, would certainJy 
bury us both ; I bade her take hold of my arm, and 
fhat I would endeavour to bring her 'into ibnte 
place of fccurity. 

^ I Ihall always look upon it as a particular provi- 
dence, that I happened on this occafion to bcundreiT- 
ed, for had I drefied myfelf, as I propofed^ when I 
got put of bed, 'in order to breakfaft with a friendj I 
(hould, in all probability, have run into the ftrecr 
at the beginning of the fhock, as the refl of the 
people in the houfe did, and confequently have had 
ipy brains dafhed out, as every one of them had > 
however, the imminent danger I was in did not 
hinder me fi-om confidering that my prefcnt drcfs, 
only a gown and flippers, would render my getting 
over the ruins almoft imprafticable : I had, there- 
fore, ftill prefcnce of mind enough left to put on a 
pair of fhocs and a coat, the firil that came in my 
way, which was every thing I faved, and in this 
'drefs I hurried down flairs, the woman with me, 
holding by my arm, and made direflily to that end of 
the ftrcct which opens to the Tagus, but finding the 
pafHige this way entirely blocked up with the fallen 
houfcs to the height of their fecond ftories, I turn- 
ed back to the other end which led into the main 
ftreet (the common thoroughfare to the palace) 
and having helped the woman over a'vaft heap of* 
ruins, with no fnaall hazard to my Own life, juft as 
we were going into the flreet, as there was one part 
1 could not well climb over without the afli(bnc« 
^ ^ > of 

of my hands, as well as feet,' I defircd her to lei* 
go her hold, which fhe did, remaining" two or three* 
feet behind me, at "which time theiae fell a vafti 
ftone, from a tottering wall, and cmflied both her. 
and the child in pieces: fo difmal a fpcdtack at 
any other time would have afrc6tcd me in the 
higheft degree, butthc dread I was in of fliaring- 
the femp fate myfelf, and the many inftances of the* 
fame kind which prefented themfelves^all aiound, 
were too (hocking to make me dwell a moment .on 
this fmgle objei5t. 

* I had now a teng narrow ftreet to pafs, whh 
die hopftfs on each fide four or five ftones high, 
all very old, the greater part already thrown 
down, or continually falling, and threatening the 
paflfengers with inevitable death at every ftcp, num- 
bers of whom lay killed before me, or what I 
thought far more deplorable — fo bruifed .and 
wounded that they could not ftir to help them- 
fclves. For my own part, as deftruftion appeared 
to me unavoidable, I only wiflied I might be made 
an end of at once> and not have my limbs boroken, 
in which cafe I could exped nothing elfc but to be 
left upon the fpot, lingering in mifer)', like thefc: 
poor unhappy wretches, without receiving the leaft, 
liiccour from any perfon. 

^ As fclf-prefervation, however, is the firft lawi 
of nature, thefe fad thoughts did not fo far prevail|. 
as to make me totally defpair. I proceeded on a% 
faft as I conveniently could, though with the utmolt 
caution, and having at length got dear of this hor- 
rid paOagCj I found myfelf fafe and unhurt in th<^ 


4t4 ^^^^ Eanbfuaki [Book VF. 

krge open (pace before St. Paul's church, which 
liad been thrown down a few minutes before, and 
buried a great part of the congregadon, that was 
gennrallf prectjr numerous, this being reckoned one 
of die nioft populous parifhes in Liibon. Here I 
ftood fome time, confidering what I (hould dp, and 
not dunking myfirlfiafc in diis fituation, I came to 
the reiblution <^ climbing over the ruins of the weft 
end c^ the church> in order to get to the river £k]c, 
diiti ought be removed, as bx as pofliUe, from the 
tottering houfes, incafepf alecond fluxk. 

^ This, widi feme difficulty, I aceompliibed, and 
here I found a prodigious concouHe of people, of 
both iiexes, and of all ranks and condidons, among 
whom I obferved fbme of the principal canons of 
the patriarchal church, in their purple robes and 
rochets, as tbefe all go in the habit of bilhops; fe* 
veral priefts who had run from the akars in their 
fiurcrdotal veftments in the midft of tiicir cejcbrat- 
ing ma(s ; ladies half drefied, and fome without 
ihoess all thefe, whom their mutual dangers had here 
aflemUed as to a place of fafety, were on their knees 
at prayers, with the terrors of death in their coun- 
tenances, every one ftriHing his breaft, and crying 
out inccflkntly, Miferecordia meu Dios. 

• In the midft of our devotions, the fecond great 
ihock came on, little lefs violent than the firft, and 
completed the ruin of thofe buildings which had 
been already much Mattered* The conftemation 
now became fo univerfal, that the (hrieks and cries 
^(Miferecordia could be diftinftly heard from the 
(Op of St. Catherine's hill, at a confidemble dkVance 

t off; 

Chap. 4^.] ' 0ttifbo». 4IJ 

cfF, whither a vaft mjinbcr of people had likewiie 
retreated ; at the fame time we could hear the fall 
of the parifti church there, wherebj^^ many perfons 
were killed on the fpot) and others mortally wound* 
ed. You may judge of the force of this (kockj 
when I inform you, it was fo violent, that I could 
fcarce keep on my knees, but it was attended with 
ibme circumftances ftill more dreadful than th^ 
former. -r— On a fijdden I heard a general outcry, ^ 
« The feais coming in, we fhall be all'loft.*-^UpoA 
this, turning my eyes towards the river, which in 
that place is near feur miles broad, I could perceivo 
it heaving and fwelling in a moft unaccountable 
manner, as no wind was ftirring; in an inft^nt there 
appeared, at fome fmall diftance, a large body of 
Water, rifing like a mountain ; it came on foam- 
ing and roaring, and ruihed towards the fhore 
with fuchimpetuoficy, that we all immediately ran 
for our lives, as faft as poffible 3 many were afhially 
fwept away, and the reft above theii* waift in water 
at a good diftance from the banks. For my own 
part, I had the rtarroweft efcape, and ibould cer- 
tainly have been loft, had I not grafped'a large beam 
that lay on the ground, till the water returned to its 
channel, which it did aimoft at the fame inftant, 
with equal rapidity. As there now appeared at 
leaft as much danger from tl^.e Tea as the land, and I 
fcarce knew whither to retire for ftielter, 1 took a 
iudden refolution of returnif^ back wit^h my cloaths 
aH dropping, to the area of St. Paul^si hew 1 ftood 
foiTie time, and obferved the fliips tumbling and 
tofling ab9Ut; as in a violent ftorn>5 fome had bro- 


4t6 Greai £arthqtiaki at DJhon. [Book Vf* 

kea their cables^ and were carried to the other 6dfl 
of the Tagus; others were whirled round withiiH 
cr-edible fwifcnefs; fcveral large, boats were turned 
keel upwards ; aad all this without any wind, which 
Jeemed the more aftonifhing. It was at the dme of 
which I am now fpeaking, thut. the fine new quay, 
built entirely of rough marble, at an immenfc ck- 
pei:ice> was entirely fwallowcd up, with all the 
. people on it, who had fled tbidier for fafety, and 
had reafon to think themfelves out of danger in 
fiich a place ; ac the fame time a great number of 
boats and imall velTels, anchored n.eir it (all like wife 
full of people, who had retired thither for the fainc 
purpofe) were all fwallowed up, as in a wbirlpooli 
and never more appeared. 

- ^ This laft dreadful incident I did not fee with 
my own eyes, as it paflcd three or four ftoncs 
throws from the fpot where I then was, but I had 
the account as here given from feveral maftcrs of 
ihips, who were anchored within two or three hun- 
dred yards of the quay, and faw the whole cataftro- 
phc. One of them in particular informed me, that 
when the fecond Ihock came on; he could perceive 
the wbok city waving backwards and forwards, like 
the fea when the wind firft begins to rife; that the 
agitation of the earth was fo great even under the 
river, that it threw up his large anchor from the 
mooriegi which fwam, as he termed it, on the 
fuifacfcof the water; that immediately upon this 
extr^of dbaty concufTion, the river rofe at once aear 
twenty jfed^ an4 in a moment fubfidcd; at which 
inftant he faw th^t quay, with the whole concourfe 

- ^ ^ of 

t:hp. 4f J ^ud^y<^ ^i^^ dejircyedi 417 

tif pcopte upon ki fink <k>wn^ and <t the ftme titne 
w^rj one of the boats a^ vefleb that a«¥^ near k 
were drawn iifto the ca^, which he fuppofes in^ 
ftantly doled, t2p(Hi them, inafmuch as nottfaejeaft 
lign of a wreck was ever iedi afterwards. This 
account you nuy give full credit tOi for as oo the 
lofs of the ve£^, it is confirmed by every body^ 
and with regard to i^e quay, I w^ myftlf a few 
days after» to convince myfelf of tfie trudi, and 
could not find even Ae ruins of a pla^e,- where I 
had taken fo many agreeable walks, as this was. 
the common i-cndetvous of the &£tory in the cool or 
the evening. I found it all deqp water^ and in fome 
parts fcarcely to be &thomed. 

' This is the oMy place 1 could leant which waa 
fwallowed up in or about Lisbon, though I faw 
many large cracks and filTures in difiererit pactSj; 
and one odd phenomenon I muft not omiti wiuch 
was communicated to me by a friend who has a 
houfe and wine-cellars on the other fide of the rivcr^ 
v\z. that the dwelling-houfe being firft terribly iha- 
ken, which made all the family run otk, there pre- 
fcndy fell down a vaft high rock near k, that upon 
this the river rofe and fubfided in the manner al«« 
ready mentioned, and immediately a great liumber' 
of foiall fiifures appeared in fevefal cottitiguoua 
pieces of ground^ whence there fpouted out likc( 
^ ja d' tsuA large quantity of fine ^itc fimd^ to 
a prckligious height. 

' I had not been kmg in the ate^ of Sc Paui's^^ 
when I felt the third ihock, which though fomewhai 
Icfs violent than the two former^ the fea ruihed in 

Vol. II* JEe again. 

^jflB > ; OtifiAff^aiioH'in ^ [Book Tl- 

^;ain,aiid. retired with. die fatne rapidity, and I rey 
:inabed up to my, kcuQPB ia w»ter, though I had gotr 
-ten qpon a: fmkll eminence at fome diftanoe frooa 
.the river, with the ruins of fevcral intervenii]^ 
jioufes to.break its force. At this time I took no- 
rticc the waters retired fo impetuoufly, that fome vcC- 
iels were kft quite dry, which rode in fcven fethom 
water: the river thus continued alternately ru(biiig 
on and retiring feveral times together, in fuch Ibrt^ 
that it was jullly dreaded Lifbon would now meet 
the fame fate, which a few yiears ago had befallen 
the city of* Lima. 

: ^ Perhaps you may think the prcfent doleful fub- 
jeft here concluded j but, alas! tlie horrors of the 
firft of November,' arc fufficient to fill a volume. As 
foon as it .grew dark, another fcenc prefented idclf 
Utde lefs Oiocking than thofe already deicribed— 
the whole city appeared in a blaze, which was. So 
bright that I could eafily lee to read by it, Ic may 
be faid, without exaggeration, it was on fire at 
kait ih an hundred different places at once, and 
thu^ continued burning for fix days together, with-? 
Ciut interminTion, or die lead attempt being made to 
ftpp.k« progrefs. 

• 5 1 could never learn, that this terrible fire was^ 
owing: to arty i^bterrancous eruption, as fome re- 
ported, but CO three caufes,. which all concurring at 
the fame time,, will naturally account for the prodi- 
gious havock it made ; the firfl of November being , 
All Saints' Day, a high feftiyal among the Ponu- 

J- , . ^ This happened in 1746.^^ 




Ehkp. 4fii] Chnfeqiienci of the Earthquake^ 41 $1 

guefe, every altar in every church and chapel 
(fome of which have nnore than t>^enty) was illu- 
minated with a numbef of wax tapers and lamps, as 
cuftomaryj thefc fettiiig fire to the curtains and 
^ tinnber work that fell with the fhock, the confla- 
■ gration foon fpread to the neighbouring houfes, 
^" and being there joined with the fifes in the kitchen 
' chimnies, increafed to fuch a degree, that it might 
^ cafily have deftroyed the whole city, though no other 
^ iaufe had concurred, efpecjally as it met with no 
^ interruptioii, 

* But what would appfcar incredible to you, were* 
' the faffe lefs public and notorious, is, that a gang of 

• hardened villains, who had been confined, and got 

s out of prifon when the wall fell, at the firft Ihock, 

were buQly employed in fetting fire to thofe build- 
ings, which flood fome chance of cfeaping the ge- 
neral deftru£bk>n. 

. * The fire, by fome medns 6r otherj may be faid 

to have deftroyed the whole city, at leaft every 

thing that was grand or valuable in it; and the 

4^mage on this occdfion is not to be eftimated. 

, * The whole number of perfons that perifhed, 

including phofc who were burnt, or afterwards 

erufiied to death whilft digging in the ruins, is fup« 

pofed, on the loweft calculation, to amount to more 

than fixty thoufand; and though the damage in 

other refpefts cannot be computed^ yet you may 

form fome idea of it, when I afTure you, that this^ 

CKtehfive and opulent city, is now nothing but a vaft 

, heap of ruins, that the rich and poor are at prefenr 

upon a level, fome thoufands of families which but^ 

E e 2 .the 

the day before had been eafy in their cii<cuoi(tafiocs;i^ 
bebg now fcattered about in the fields, wandng 
every conveniency of lifr^ and findkig none able t» 
relieve t]iem* "^ 

' A few days after the ftft confEeraotioii was over,^ 
I ventured down into the city^ by the (afeft wxf% i 
could pick 0Ut» to fee if the^e was a peflibiiity of 
getting any thing oot of my lodgings, but die ruins 
were now ib augmented by the late fire^ that I wa» 
ib far from being abk to diftingttt& ^ mdividual 
fpot where the houfe ftood, that I could not even 
diftinguiih the ftreet, amtdS: the mountains of ftonc 
and rubbilhr whkh rofe on every fide. Some days 
after, I ventured down again wkh fevsenri portet^ 
who, having iDog plied in }^it parts of tte town^ 
were well acquainted with the fituadon of partkiilay 
houfes;. fa^ riieir afliftance, f at laft difcovered the 
fpot^ bm was foofv convinced, that to dig ibr any 
thing thercy befKks the cknger of fucH an attempt, 
would never anfwer the esq^ence. 

* On both the tin^s when I attempted to make 
this fruitkft fcarch, efpecially the firft, there came 
fuch an intokrabk fiiendi firovn the dead bodies, 
that i was ready to faFnt a^ay, and though it did 
not (eem fo gretft this laft time, yet it had nearly 
been more final to me> as X contracted a fever by 
it, but of which; God be praifed, I feon got iJk 
better. However, this made me fe cautious for die 
future, that I avoided paffing near cettain places, 
where trie ftench was fo exceffive that peopfc began 
to dread an infection : a gentleman told me, that 
going into the towna few days after the earthquake, 


Chap. 46.] EarAfMhesm G^i^uu d^t 

l» faw ikvcnl boditft lyi^ 10 the ftrtctSt hwc 
bofiMy mai^led^ as he luppofed^ by die dogs^ 
^bers half buriit^ €omt qiu£e roafted ; tod that 
in ccitain placesy particularly Mar the ^oors ^ 
i^burchesy thqr lay in vaft heaps fi^td one upoe 

The year 47S j was fatalfy^ inarked by the defola- 
tioo of £>ine of the moft ferule^, moft beautiful, 
and itic^ cefebraled provinces of Europe* The 
two Calabrtas» iMch a part of Sicily, were doomed 
10 be a fcoie of the moft tremendous^ abd the moft 
Saal earthquakes that ever were kztownt even in 
^faofe volcafiic regions. The &rft (hock happened 
about «oofi> on the 5 th of February^ and wasib 
violent as to Involve almoft the whote .of Calabria 
In ruin. This was but the commencement of a fuc- 
ceflion^of eaxthquflkes, wl^ch beginning from the 
city of Am^tea^ on the coaft of the Tyijrhene iesL 
proaxdcd along the weftern coaft toC^pe SparQ- 
vento>» and i^ the eaftern as far as Cape D* Alice ; 
^during the virhole of which (pace not it toum waf 
Jcft undeftroycd. %t 

During two years repeated OiQfks continued Uf 
agitate ihe affr^ted minds ^f the inhabitants <^ 
Calabria and Sicily, but the principal mifcl^iefsarofe 
in the months of February and March in the firft 
year. For feveral months the earth continued in an 
4]nccaling nremcH*, wliich at certain intervals increaf- 
ltd to violent (hock% fome of which were beyond de^ 
feription dreadfU. Thefe Ihocks were fometimea 
horizontal, whirling Eke a vortex ; and fometimea 
by pulfations or beating from tlie bottoni upi^ards, 
E e 3 and 

4^2 Great Eanbqltakes [Book VI, 

and Wf re at times lb violent that the heads of tiie 
largeft trees almoft touched the ground on eidicr fide. 
The rains, during a great part of the timet were «»- 
tinual and violent, often acconipanied with li^^- 
ning, and furious gufls of wind. All that part of 
Calabria, which lay between the 38 th and j^tfa 
degrees, aflfumed a new appearance. Hbuies, 

.churches, towns, cities, and villages, were buried 
in one pfomiicuous ruin. Mountains were detach- 
ed from their foundations, and carried toaconfider- 
able diftance *. Rivers difappeared from dieir 
beds, and again returned and overflowed the adjacent 

.country f. Streams of water fuddehly gulhed out 
of the ground, and fprang to a confid^rable height. 

. Large pieces of the furface of the nkun^ ieveral 

^ Sir William Hamilton, whofe ardeot and Ifiudahle fpim ^f 

, inquiry occafioned his viiiting Calabria and Sicily doling this 
calamitous feafon, accounts for the removal of a mofintahi of 
about two hundred and fifty feet in heighth, and about four 
hundred feet in diameter at its bafis, from the different Qacore of 
its inferior and fuperior flnita. The under part being more (oM 
and compadl, was more flrongly a^ted upon by the violent mo- 
tion of the earth, .and the volcanic exhalations, which drove 11 
to the didance of fome hundred yards from its original (cite, 

* where it lay in con^fed blocks, after having left .the fuperior 
^ Uratum, which » with its trees and vineyards* was parried in afi- 
other diredlion to the diflapce of fqur miles. . 

f The fame philofopher accounts for this phenomenon 
by fuppofing the firft impulfe of the earthquake to have 

- come from the bottom upwards, which ndfing the farftce of the 
ground^ the rivers which are not deep maft naturally diiappcar ; 
but the earth returning again with violence to its former Itv^ 
the rivers mud as naturally return and overflow their banks; at . 
tlie fame time the boggy grounds being fuddcnly dcprdTcd, 

' would force out the water which lay hid under their furface. ' 


CShap;" 4^ 'in Caldbrid. ' ' 4iy 

acres* in extent^ were carried five hundred feet from* 
£heir former fituation down into the bed of the* 
river, and left Handing at nearly the diftance of ^ 
mile, furroynded by large plantations of oIive$ and 
mulbei-ry tree3, and corn growing as well upon therii 
As upon the ground from which they were feparatcd'. 
Amidft thefe fccnes of dcvaftation, the efcapes of 
fbme of the unhappy fufferers is extremely wonder- 
ful. Some of the inhabitants of hpufes which were 
^bwn to a confiderable diftance, were dug out from 
their ruins unhurt. But 'thefe inft^nces were few, 
and thofe who were fo fortunate as to preferve their 
lives in fuch fituations, were content to purchafe ex- 
iifende at the expence of broken limbs and the moft 
dreadful contuGons. ! . ^ 

During this calamitous fcene, it is impoflible to 
conceive the horrors and wretchednefs of the unhappy 
inhabitants. The jaws of death were opened to fwal- 
low them up ; ruin had feized all th^ir pqireiTions, 
and thofe dear connexions to which they might 
have looked for confolation in their forrowjs, were 
for ever buried in the mercilefs abyfs, AU was 
ruin and defolation. Every countenance indicated 
the extremity of affliAion and defpair; and the 
whole country formed a wide fcene of undcfcribablp 

One of the moft remarkable towns which was 
deftroyed was Cafal Nuova, where the Princefs 
Gerace Grimaldi, with niore than four thoufand of 
her fubjefts, periftied in the fame inftant. An 
inhabitant happening to be on the fummit of a 
* neighbouring hill at the moment of the fhock, and 
E c 4 looking 

4H. Eftrthfui$} m Caldria. (Book. VI^ 

looking earadUy back to the itfideacic f;^ his &« 
pfiily^ could fe.e no other remains of it than a wkite 
cloud which proceeded fronvthe ruins of the houlcs* 
At Bagnaraj about three thoqfand perfbns were 
killed^ and not fewer at Radicina ^a Palnna* At 
Terra Nupva four thoufand four hundred periflicd, 
and rather more at SemniarL Thp inhabicaacs of 
Scilla elcaped from their houfes on the celebrated 
rock of that name;"and, w^th their prince, dcfccnd^ 
led to a litde haibpur at the fpot of the hiU^ but, i^ 
thccourfe of the nighty a ilupendous wave^nvbicH 
is faid to have been driven three miles over laod^ 
on its return fwcpt away the unfortunate princei 
v^ith two thOufand foijr hundred and feyj^nty-thrfe 
of his fiibje£ts. |t is computed that not le^ thai) 
fort7 thoufand perfbns periihed bf this es^* 


Boat vn, 

OF W A T M ^ 


Chap. I. 


StiUi.'^Fkrmttini Experimiittr^ Vafeur,,~^:^iMimts t^m 
^mng the Fvrce of Vapwr^^-^ttam En^ine.'^^Ict.'t^hiwnmMa 
pf Frei9uug.^^0/TbmmMg,''^H^ater expanJed in the State ^f 
Ice^r^Imminfi Force exerted hy Water m pa(fing to that State^^^ 
J/ny Ice it not perfeSly tra^fparent^ 

WATER was tmivcrfally confidered as a 
fimple elementary fubftance tiH the (%e« 
mifts of the prcfent age proved, by experiments, 
the fubftance of which has been ftated in a preced- 
ing vohime ^^ that it is in reality a compound body« 
Its principles have been afcertained both by com« 
pofition and decompofition; and one hundred parts 
of water are found to confift of eighty- five parts of 
otygen> and fifteen of hydrogen, or the bafis of 
inflammable air. 


ir B<K)k V. Clul^ L 


42$ ^Ireehakrtffiraiir. [Book Flfi 

This very ufeful and ncceflary fluid prefents idelf 
to our notice in three diftind fbrms^ namely, in 
its liquid ftatej ^ti^he ftatfiQf vapour or fteam, and 
laftly in its frozen ftate. Of thefe I (hall (peak m 
their order. 

Water, wh^ jJUre^aml iiilts fluid ftate, is tranr- 
parenr, colourlefs, and without fmelL It adheres to 
moft bodies iVhich come in cc^nt^ with it, it per- 
vades porous fublTances, diiiblves gummy and faline 
matters, and extinguiflies fire. 

Water, when fluid is not in its mo(t fimple ftat^ 
for its fluidity depends oh a certain quantity of ca- 
loric, or tbe-mjitter of heat, which enters ii^u com- 
bination with it, and infiauating itfelf between the 
particles of the water, renders them capaUe of 
moving^ in all dirc6Hons. 

We are fuppiied with water either from the at- 
niofphefc, whence it defcends in the form of ram. 
Kail, or friow, or from the eartTi which fends it 
forth in fpriiigs and rivulets. In the former cafe 
the watery exhalations drawn from, the fea, and the 
lurfac^ of thie earth by the fun*s heat, form clouds, 
whofe particles beii^g afterwards condenfcd, fall 
fe^ck agaifi in- ftiov^ers. In 'the latter, the water 
Vpich flills on the tops of mountains, and other lofty 
/ituacigns, penetrates tl>e earth, and, after paifmg 
4pwn wards, breaks forth at fome fiflure or aper- 
ture at a diftaace from its fourjce. 

The quantity of water j^ttraded from the fur- 
face of the globe is almofl: incredible. Dr. Jial^ 
ley has calculated that portion which is yielded by 
the fea, to be at iiic rate of one cubic inch from 
;* : . every 

^hap, 1.3 Jncompreffihli andElaftic Fluids. 4:27 

levery ten inches of furface in twelve hours *. Tp 

form an adequate idea of this, let us fuppofe only 

lialf the globe to be cohered by the fca. The wholf 

furface of the earth being about 25,7^7,278 leagues^, 

that of the lea will confequcntly be 12,898,639. 

.Suppofing the evaporation which takes place in 

twelve hours to be that aboye mentioned, without 

having any regard to what is evaporated from the 

whole of the land, or from the fea during the other 

twelve hours, it will be found that the atmofphefe 

has taken up no lefs than 20,302,535, i7'7,834, or 

more than twenty millions of millions of cubic feet 

of water ; an enormous quantity, and much more 

than ftifficient to fupjdy all the rivers that interfed 

the different quartei^s of the globe f . 

What particularly diftinguilhes water, and thofe 
fluids which are of a fimilar confiftehce, and in 
common language are termed liquids,, fronci thofe 
fubtilc fluids which were treated of at large in tlie 
preceding volume, is, that the former are not, like 
the others, poffeflfed of that furprizing elafticity 

* SeeBifhopWatfon's Calculation, voI.Lp. £22. 

f There will poffibly be apparent, in this part of the work, 
fome degree of repetition when compared with what was faid 
of vapour in the firft bock. It was then neceffar/ to fpeak of 
vapour, in explanation of the properties of heat; it is now 
i^cceflfary tp treat of k in conne^on with the floid of which k 
Js ufually formed ; and I conceive it bettef to 4o this, with the 
rifle of fome repetition, than to refer to a former volume^ both 
becaufe it will ferve more firmly td imprefson the minds of 
young readers fome'of the moft important do^rines of philofo- 
phy : an4 becaufe what may now appear ats repetition, is, in 
^his placp, mixed with new fa£b, which could not be pre^ 
Viouiiy ihtroduced. ' ' 

^ which 

4^8 Fkre^iine ExferimM^ [Book VIL 

which admits of the volume c^ fluid beixig. coo- 
denied into a fmall compals ; but^ on the GaDtnuy, 
may be conGdered as incapable of compreiliocr^or ac 
leaft are comprefGble in a very flight degree. The 
Florentine academicians filled a globe of gold witk 
water^and compreflled it with inimenfe force; the firft 
f^Std of this compreflion was, that the ball was cod- 
fiderably heated by the emiflion of latent heat from 
fhe water, and afterwards the fluid forced its way 
through the pores of the go)d> or throi^h certaia 
^cavities, tod appeared In drc^s on the external fur- 
fiiee. The condufion, however, which was haftily 
drawn froai this experiment, that water, in its liquid 
fiate, is abfolutely void of all elafticity, is not war- 
rantable. Since other experinients flbew tliat water 
as well as mercury will yield, in a certain degree, to 
the prefTure of the air in a condenfing machine, 
as Mr. Canton proved by including it in a glais 
v^Stlj with a narrow neck or ftcm nicely graduated i 
its condenfation appears proportioned to . the force, 
and as ibon as t^e prefllure of the air is removed, the 
ifluid will be obfcrved gradually to recover its ac- 
cuftomed dimenfions. 

• When water becomes heated to a degree beyond 
that of the air upon its furfacc, the matter of heat, 
which has a conftant propenfity to difFufe itfdf 
fcqually through all bodies with which it is in con* 
taft, rifcs and carries with it part of the water, 
ycJuch it converts into an elaftic fluid or vapoun 
UntU the water, however, arrives at the boiling 
point, the eyi^)oration is very gradual ; but when 
ijiis happens it becomes very rapid, and the part of 
" ' the 

^ Chap. I.] Water in the State of Vapour. 419 

the water which is moft heated, being converted 
I into vapour, rifes iuddenly to the furfaccj and oc^ 
{ cafions confiderabk agitation. 

Ebullition requires a determined degree of heat» 

\ becaufe the fteaoi cannor be fbrnijcd within the 

I ijvacer, imlefs it is ftrong enough to overcome the 

I adtual pfdTure of the &uid and air incumbent on 

it. But in ordinary evaporation, the vapour is 

farmed at the furface of the water; and has therefore 

no other preffure to overcome than that of the at-. 

, mofphere. The elaftic fluid, however, which is 

( formed by orditiary evaporation is different from 

[ that produced by ebullition, for the latter always 

returns to the ftate of water by a diminution of 

j temperature, whereas the former is reduced almofi: 

to the ftate of a permanently elaftic fluid by mixture 

with air. 

We find that all fluids boil more eafily in pro- 
portion as the preflure of the atmofphere is remov- . 
ed; whether this is effcfted by afcending a moun- 
tain, or making ufe of the air pump. M. Lavoifier 
fays, that if the weight of the atmofphere was only 
equal tt) between twenty or twenty-four inches of a 
column of mercuryi inftead of twenty-eight inches, 
we fheudd nerer be able to obtain xther in a liquid 
ftate, atMeaft ih fummer; and that die formation 
rf sedier miA confcquently be impoflible upon 
mountains of a moderate degree of elevation, with- 
out employing extraordinary means of compreffion 
for its condenfation. Upon the whole, it appears 
nioft probable that all bodies are capable of exifling 
in a folid^ a liquid, and on Mrkbrm ftate ^ that the 
i firft 

^jo IVater in Ckuis. [Book Vtti 

firi): is the moil (imple ftatc of all bodies, and di^ 
the two others depejid on combinations with dific- 
rent quantities of the matter of heat, of which tfae^ 
aeriform ft^te requires by far the mod. 
. Vapour> as it firft rifcs fronn boiling water, i^ 
invifiblc> but as it mixes with tl^ air it is deprived 
of part of its heat, returns to its fluid forro, arid the 
very minute drops of .water which are produced 
afcend in a copious cloud of a white or light-gre-/ 
colour. Vapour is the more readily difcernab c in 
proportion to the coldnefs and humidity of the at- 
mbfphere. The cloudy appearance of fteam is 
occafioned by the difficulty with which its parncles 
are feparated and diflblved in the atmolphcrcj the 
difficulty is increafed in proportion to the coldnefs 
and humidity of the air> and this is the reafbn chat- 
the moifture exhaled with the breath, is vifible ii| 
winter and not in fummer. 

It was ftated in a former volume, that* the combi-. 
nation of the matter of heat or caloric, with die 
particles of water, in that degree which conftitutes 
fteam, rarifies them fo exceedingly, as to occafion 
them to occupy a fpace fonfic hundred times greater 
tlhan the original bulk of the fluid, and it is that alio 
which volatilizesi and enables them to afcend dirough 
the air, and to overcome its refiftanccrf 

But when fl:eam is expofed to a ftill greater degree 
of heat, its volume is augmented fl:ill more conli- 
derably. ,That heat which makes water boil, and 
which rarifies it only one twenty-fixth> rarifies its 
vapour to eighteen hundred d/ncs.the bulk of die 
water which produced it. ..This may be yery.rpadily 
4 demonftratcd. 

ChajK' I .] ; IVater in tbe^Siah of Vapour, j^j^ 

dcmonftrated^.bx taking a glafs tube> at. one end of 
3vhich is a bul^ of two inches in diameter, and 
dropping into it alRhgle drop of water, the diame- 
ter of which we will fuppofc to be one- tenth of ah 
inch. TJie fqiiares.of thefc two fpheres, with regard 
to each other, will be as 1800 are to one. Upon 
lieatiog the bulb of the tube over the flame of a 
Ipirit lamp, the air will firft be expelled, and after- 
wards the drop of, water will be converted into 
fteam, and take poffcffion of the whdie of the 
bulb ; as may be proved by plunging the mouth cif 
the tube into cold water^ and fufiering rhe fteara 
within the bulb to return to its fluid ftate. In this 
cafe, the prefllire of the atmofpherc will caufe the 
water to rufli into the tube, and to occupy that 
fpace within the bulb, which before was occupied 
by the vapour, and thus the fa<St will be afcertained. 

If, however, any obftaclc is oppofed to the ex- 
panfive force of fteam, the heat augments its refift- 
ance in a degree proportionate to the augmentation 
of its volume. The power of refiftance afibrded by 
the vapour of water Js prodigious, and has of lace 
years been made fubfervient to fome mechanical 
purpofcs of, the greatefl: importance. Mufchen- 
brook has proved by experiment, that the force of 
gunpowder is feeble, when compared to that of rifirig 
ftearB. An hundred and forty pounds of gunpowder 
blew up a weight of thirty tboufand pounds ; but on 
the other hand, an hundred and forty pounds of 
Wer, converted by heat into fteam,iifted a weight 
6ffcvcnty-fcvcn*thoufand pounds,* and would lift i 


43% "ft^ Stem [Book TIL 

much greater^ if there were means of giving the 
(team greater heat with fafet^^ for the hotter th& 
fteam die greater is its force. 

The ftcam-engine, to which I had formerly occa- 
fion (lightly to advert *, is a machine which may b^ 
and is occafionally applied to various mcchanicd 
purpofcs where great force is required, but whicji 
has hitherto been principally ufed to dear mines 
j&om watery and to raife water to a proper height 
for the fupply of cities. In thcfe cafes, the espan- 
five power of fteann is fo managed as to operate qd 
immenfe water pumps, which could notconveniei^ 
be worked by any other means. In order to give 
the reader a fuperficial idea of this machine, let us 
imagine a common pump prepared, and chat wc 
want to move the handle of this pump upwards by 
the force of fteam only* In the firft place, let us 
fuppofejthat the handle of the pump^ or fbmething 
connected to it, was Co contrived as to admit d[ 
being inferted in the barrel of a gan, or (bme cylin^ 
drical tube» fet upright over a cauldron containing 
boiling water- Next let us fuppofe, that the fteam 
could be admitted into the tube, through the touch* 
hole^ and fo confined as to pafs only by that way. 
Now as the fire begins to dilate the fteam, a part 
of it will enter the tube by the' touch-hole, and this 
wiU'prefs up the pump, whioh Is fuppofed to be fo 
fitted to the tube as to prevent any part of the fteam 
from efcaping. In this- way the punap handle 
would be driven quite out at the mouth ot the tub^ 

* See vol. i. p» I to. 


Chap, r.] Engine. 4J3 

but let us inlagine, that before this can happen a 
valve is opened^ which allows a fmall quantity of 
cold water to be fpouted into the tube, which effec- 
tually and inftantaneouliy deftroys, or, more pro- 
perly, condenfcs the fteam. The tube being now 
left empty, there is nothing to counteraft the pref- 
fure of the atmolphere, which again forces down the 
handle into the tube, into which nofteam is per- 
mitted' to enter, on account of a valve which now 
ftops the touch hole below; but whm the handle 
is thus preffed down, the valve below is again open- 
ed, and new ftcam entering again prcffes the handle 
upward; when the handle comes near the top, 
the fteam is again cooled and condenfed as before^ 
and the handle is again preffed down by the weight 
of the atmofphere* In this manner it is alternately 
driven upwards and downwards by the expanfive 
power of the fteam and the preffure of the external 
air, and ^orks th^ pump with unwearied aifiduity. 

Though the princi{)lc, however, is plain, the 
machinery is complex in the fteam engine; but the 
annexed plate IV. will probably render it tolerably 

In fig. I. A reprefents the fire-place under the 
boiler, for the boiling of the water, and the afh^ 
hole below it. 

B, the boiler, ftllcd with water about three feet 
above the bottom, made of iron plates, 

C, the fteam pipe, through which the fteam 
paffes from the Boiler into the receiver. 

Vol. H. F f D, the 

4J4 51&^ S^^^ [Book VII. 

D| the receiver, a clofc Iron ycffel, in which is 
the regulator or fteam-cock^ which opens and 
Ihuts the hole of communication at each ftrokc. 

E| the communication pipe between the receiver 
and the cylinder 5 it rifes five or fix inches up, in 
the infide of the cylinder bottom, to prevent the 
injeftcd water from dcfcending into the receiver, 

F^ the cylinder, of caft iron, about ten feet 
long, bored fmooth in the infide ; it has a broad 
flanch in the middle on the outfide, by which it is 
fupported when hung in the cylinder beams* 

G, the pifton, made to fit the cylinder cxaAly : 
It has a flanch rifing four or five inches upon its 
upper furface, between which and the fide of the 
cylinder a quantity of junk or oakum is ftuflfcd, and 
kept down by weights, to prevent the entrance of 
air or water and the efcaping of ftcam. 

H, the chain and pifton fiiank, by which it is 
connected to the working beam. 

1 1, the working beam or lever : it is made of 
two or more large logs of timber, bent together at 
each end, and kept at the diflanc^ of eight or nine 
inches from each other in the middle by the 
gudgeon, as reprcfented in the plate. The arch- 
heads, 1 1, at the ends, arc for giving a perpendicular 
dircftion to the chains of the piftpn and pump- 

* K, the pump-rod which works in the (uckii^ 

L, and draws the water from the bottom of the 
pit to the furface. 

M, a 

M>. a ^dcrri, into which the wafier cUawri otit of 
the pic is coildufted by K trough^ fo a^ to keep it 
always full; and the fuperflUDQs water is carried off 
by another trough, 

• Nt the jack- head pumpi whicfi is a fucking- 
pvmp wrpught by a fmall lever or working-Jbeam^ 
by means of ^ chain coiinedked to the great beam 
or lever near the arch g aC the inner end^ and thrf 
pump rod at the oiuter end. This pump commonly 
ftands near |he corner of the front of the hoirfe, and 
raifes the dolumrt of wateiup to the ciftern O, into 
Which it is conduiJted by a trough. , 

O^ the jack- head ciftern for fupplying the int 
JcdlioQi which is always kept full by th? pump N| 
it is fixed fo high as to give the jet a fuflcient velo« 
city into the cylinder wl>en the cock is opened^ 
This ciftetn has a pipe on the opppiice fide for con- 
toying away the fuperfluous watet-. 

P P, the injeftion-pipCi of three or four inches 
4iameter| which tUrns up in a cufve at the lowe* 
cnd^ and enters the cylinder bottom ; it has a thin 
plate of iron Upon the end ay with three or foui" 
adjutage holes in it> to prevent the jet of cold wate# 
of the jack-head ciftefn from fiying up againft- the 
t>ifton, and yet to condenfe the fleam each ftrgke^ 
Vben the injefkion-cock is open^' 

iy a valve upon the upper end of the injeftioa* 
J>ipc vfithin the ciflern^ which is Ihut when the en* 
gine is not workings to prev«^nt ahy wafte of the water. 
/, a fmall pipe which branches off from the in^- 
}e£tion*pipe/ and has a fhiall cock to fupply the 
plfton with a little water to keep it air-tight. 

Ff2 Qi^thc 

43^ ne Steam^ [Book VII. 

Qj^ the working plug, fuipeaded by a chain to 
the arch g of the working beam. Itis uluaily a 
hiavy piece of timber, with a flit vertically do'wn 
its middle, and holes bored horizontally through it^ 
to receive pins for the purpofc of opening and 
fhuttmg the injedion and ftcam cocksj as it aC- 
cends and defcends by the motion of the working 

b, the handle of the fl:eam-cock or regulator. 
It is fixed to the regulator by a fpindlc which comes 
up through thfc top of the receiver. The regulator 
is a circular plate of brafs or caft iron, which is 
moved horizontally by the handle b, and opens or 
Ihuts the communication at the lower end of the 
pipe E within the receiver* ^It is reprefented in 
the plate by a circular dotted line. 

i I, the fpanner, which is a long rod or plate of 
iron for communicating motion to the handle of 
the regulator, to which it is fixed by means of a 
(lit in the latter, and fome pins put through to 
feften it. 

kl, the vibrating lever, called the Y, having 
the weight k at one end and two legs at the other 
end. It is fixed to an horizontal axis, moveable 
about its cfPter-pins or pivots m », by means of the 
two ihanks cp fixed to the fame axis, which are 
alternately thrown backwards and forwards by 
meaqs of two pins in the working plug; one J)in on 
the outfide deprefling the fiiank o, throws the 
loaded end * of the Y from the cylinder into the 
pofition reprefented in the pbte, and caufes the leg 


Chap. !•] Engine. 437 

/ to ftrike «gainft the end of the lpanner> which, 
forcing back the handle -of the regulator or fteam 
cock, opens the communication,' and permits the 
fleam to fly into the C3rlinder. The pifton imme- 
diately rifmg by the admiflion of the fteam, the 
working beam 1 1 riles 3 which alfo raiies the work- 
ing- plug, and another pin which goes through the 
flit raifes the fhank p, which throws the end k of 
ihe Y towards the cylinder, and, ftiiking the end 
of the fpanner, forces it forward, and fhuts the re- 
gulator fteam-cock. 

qr, the lever for opening and fhutting the injec- 
tion cock, called the F. It has two toes for its 
center, which take between them the key of the 
.injeftion cock. When the working-plug has af« 
ccnded nearly to its greateft height, and fliut the 
regulator, a pin catches the end q of the F and 
raifes it up, which opens the injeftion-cock, ad- 
mits a jet of cold water to fly into the cylinder, 
and, condenfing the fteam, makfs a vacuum^ 
then the preflTure of the atmofphere bringing dpwn 
the pifton in the cylinder, and alfo the plug-frame, 
another pin fixed in it catches the end of the lever 
in its defcent, and, by prefllng it down, fhuts the 
injedlion-cock, at the fame time the regulator is 
opened to admit fteam, and fo on alteriiately; 
when the regulator is fhut the injeftion is open, and 
when the former is open the latter is fhut. 

R, the hot- well, a fmall ciftern made of pUnks, 
which receives all the waftc yr^ttv froip riic cylin- 

F f 3 S, the 

43^ Tl^f Sitam [Book VII. 

S, (he fiok^pit to convey away the water ixrhicb 
is injected into the cylinder at each ftroke. Its 
upper end is even with the infide of the cylinder 
]bottom> its lower end has a lid or cover moyeabl^ 
on a hinge^ which ferves a$ a yalve to let out the 
inje6bcd water^ and fhuts clofe each ftroke of the 
, engine^ Xp |>revent the water being forced up agaiii 
when the vacuum is made. 

T, the feeding-pipe, t;o fiipply the boiler with 
water from the hot -well. It has a cock 'to let in 
a large or fmall quantity of water^ as occafion re- 
quires, to make up for what is evaporated; it goes 
pearly down to thje boiler bottom. 

U, two gage cocks, the one larger than the 
Otheri to try whcp a proper quantity of water is in 
the boiler : upon opening the cocks^ if one gives 
jleam and the other water, it is right; if tKey both 
give fteam^ there is too little water in the boiler j 
and if diey bqth give wai^r, there is tqo much, 

W, a plate which i's fcrewed on to a hole on the 
fide of the boiler, to allow & paiTage into tho 
boiler fpr tl^e convenience of cleaning or repairing 
It. ' ' 

X, the (l^am-ciack or puppet valve, which is a 
brafs yalve on the top of a pipe opening into the 
boiler, to let off the fteani when it is too (Iroi^. 
it is Iqad/ed wijth )ead, at the rate of onr pound tQ 
an inch fquare; and wbep (he fteam is nearly 
Jlrong enough t^ keep it open^ it will do for the 
working of the engine. 

f, the fnifting valve, by which the air is difcharged 
jfrjpm the cylinder each ftroke, which was admitted 



Chap. I.] JSngwfp 439 

with the injcftion, and would othcrwife obftruft 
the due operation of the engine. 

//, the cylinder-beams; which are ftrong joifts 
going through the houfe for fupporting the cylin- 

V, the cylinder cap of lead, foldered on the top 
of the cylinder, to prevent the water upon thie 
pifton from flafliing over when it rlfcs too high. 

w, the wafte-pipe, which condudb the fuper- 
fluous water from the top of the cylinder to th^ 
hot- well. 

X Xy iron bars, called the catch-pins, fixed hori- 
zontally through each arch heacj> to preyent the 
beam defcending too low in cafe the chain fbould 

yyy two ftrong wooden fp rings, to weaken the 
blow given by the catch pins when the ftroke is 
too long* 

z 2, two friftion-whecls^ on which the gudgeon 
or center of the great beam is hung; they are the 
third or fourth part of a circle, and move a little ^ 
eac^ way as the beam vibrates. Their ufc is to 
diminiQi the friftion of the axis, which, in fb heavy 
a lever, Would othcrwife be very great. 

When this engine is to be fet to work, the boiler, 
muft be filled about three or four feet deep with 
water, and a large fire made under itj and when 
the fte^m is found to be of a fufficienc ftrength by 
the puppet- clack, then by thrufting back the 
fpanner, which opens the regulator or fteam-cock, 
the fteam is admitted into the cylinder, which 
raiies the pifton to the top of the cylinder, and 
' F f 4 forces 

440 ^^ S^^'0»^ [Book VII. 

force? out all the 'air at the fnifting valve; then by 

turning th^ key of the injeftion-cock, a jet of coki 

^ater is admitted into the cylinder, which condenfa 

the fteam and makes a vacuum -, and the atmo- 

fphere then prefling upon the.pifton, forces it down 

to the lower part of the cylinder, and makes a 

ftroke by raifing the column of water at the other 

* end of the beam. After two or three ftiokes arc 

made in diis manner, by a man opening and fhut- 

png the cocks to try if they arc right, then the pins 

"^ay be put into the pin-holes in the working- plug, 

and the engine left to turn the cocks of itielf, 

which it will do with greater exaftnefs than an^ 

i)ian ,can do. 

Many important improvements have been lately 
made in the ftcam engine by the ingenious Mr. Watt, 
of Birmingham* Hp has contrived to prefervc an 
uniform heat in the cylinder of his engines, by fuf- 
fering no cold water to touch it, and by prote6ting 
It from the air, or other cold bodies, by a furround- 
ing cafe filled with fteam, or with hot air or water, 
and by coating it oyer with fijbftances that tranfmit 
heat (lowly. He makes his vacuum to approach 
nearly to that of the barometer, by qondenfing the 
ftcarr> in a feparate veffel, called the condenfer, 
which may be cooled at pleafure without cooling 
the cylinder, either by an injeftion of cold water, 
or by furrounding the condenfer with it, anH gene- 
rally by both. * He extrafts the injedion water 
and detached air from the cylinder or condenfer 
by pumps, which are wrought by die engine 
jtfelf, or blows them out by the fteam. As the 

* entrance 

Chap. I.] Engine. 441 

entrance of air mto the cylinder wouU ftop the 

operation of the engines^ and as it is hardly to be 

cxpeftcd that fuch enormous piftons a3 thofe of 

fteam engines can move up and .down, and yet be 

. abfolutely tight in the common engines, a ftream 

of water is kept always running upon the piftoo^ 

which prevents the entry of the air; but this mode 

of fccuring the pifton, though not hurtful in the 

, common ones, would be highly prejudicial to the 

new engines. Their pifton is therefore made more 

accurately; and the outer cylinder, having a lid, 

covers it, the fteam is introduced above the pifton; 

and when a vacuum is produced under it, a£b 

upon it by its elafticity, as the atmofphere does 

upon common engines by its gravity. This way 

of working cffeftually excludes the air from the 

inner cylinder, and gives the advantage of adding 

to the power, by increafing the elafticity of xht 


In Mr. Watt's engines, the cylinder, the great 
beams, the pumps, &c. ftand in their ufual po« 
fitions. The cylinder is fmallcr than ufual, in 
proportion to the load, and is very accurately ' 

In the moft complete engines, it is furrounded^ 
at a fmall diftance, with another cylinder, furnifhed 
with a bottom and a lid. The interftice between 
the cylinders communicates with the boilers by a 
large pipe, open at both ends, fb that it is always 
filled with fteam, and thereby maintains the inner 
cylinder always of the fame heat with the &ezm, 
and prevents any condenfation within it>^ which 


442 the Sieam [Book Vll 

would be more detrimental than an equal conden- 
iation in the outer one. The inner cylinder has a 
4)ottom and pifton as ufual i and as it does not 
reach up quite to the lid of the outer cylinder, the 
fteam in die incerftice has always free accels to d^ 
upper fide of the pifton. The lid of the outer 
cylinder has a hole in its middle j and the pifton 
tod, which is truly cylindrical, moves up and 
down through that hole, which is kept fteam-tighr 
by a, collar of oakum fcrcwed down upon it. Ai 
the bottom of the inner cylinder, there are two re- 
gulating valves, one of which admits the (team to 
pais from the interftice into the inner cylinder 
below the pifton, ol- (huts it out at pleafurc; Ae 
pther opens or (huts the end of a pipe, which leads 
|fo the conden(br. The condenfer conlifts of one 
pr more pumps furnilhed with clacks and buckets 
(nearly the fame as in common pumps) which arc 
wrought by chains fattened to the great working 
beam of the engine. The pipe, which comes 
from the cylinder, is joined to the bottom of the/& 
pumps, and the whole condenfer ftands immeifcd 
an a cittern of cold water fupplied by the enginC' 
The place of this cittern is either within the houfe 
fir under the floor, between the cylindfer and tbc 
lever wall; ot without the houfe betwcrn that waB 
and the engine Ihafr, as convenicncy may require. 
The condertfer bejng exhaufted of air by hhwlngt 
jtQd both the cylinders being filled with fteam, ^ 
regulanng valve which admits tbc fteam into the 
inner cylinder is (hut, and the other regulator 
^hich caaimmicates with th^ ^copdenier is opened, 


Ghapt 1.3 Engine. 443 

and the (team rufhes into the vacuum of the con^ 
denfer with violence; but there it comes into 
contaA with the cold fides of the pumps and pipes> 
and meets a jet of cold water, which was opened at 
the fame time with the exhauftion regulator 1 
thefc IniBindy deprivre it of its heat, an^ reduce i( 
to water; and the vacuum remaining perfcft* 
more fteam condnues to ru(h in, ahd be condenfed 
until the' inner cylinder is exhaufted, Thch the 
Hqam which is above the pifton, ceafing to be 
counteracted by that which was below it, acts 
upon the pifton with its whole elafticity, and (brccs 
It to dcftrend to the bottom of the cylinder, and lb 
raifes the buckets of the. pumps which are hung to 
the other end of the beam. The exhauftion re- 
gulator is now (hut, and the fteam one opened 
again, which, by letting in the fteam, allows the 
pifton to be pulled up by the fuperior weight of 
the pump rods; and fo the engine is ready for 
another ftrokc. 

But the nature of Mr^ Watt's improvement will 
be perhaps better undcrftood from the following de- 
fcriprion of it, as referred to a figure.— The cylinder 
pr fteam yeflfel A, of this engine (fig. a.) is (hut at 
bottom and opened at top as ufual, and is included 
^n an outer cylinder or cafe BB, of wood or metal, 
covered with n^aterials which tranfmit heat (lowly. 
This ca(c is at a fniall diftance from the cylinder, 
and clofe at both ends» The cover C has a hote m 
it; through which the pifton rod E Aides ; and hear 
the bottom is another hole F, by which the fteam 
from the boiler has always free entrance into this 


444 ^^^ Steam E^me. [Book VII. 

cafe or outer cylinder, and by the interfticc GG 
between the two cylinders has ^cceis to the upper 
fide of the pifton HH. To the bottom of die 
inner cylinder A is joined a pipe I, with a cock or 
valve K, which is opened and fhut when nectffary, 
and forms a paflage to another veflel L. called a an- 
denfer^ made of thin metal. This veflel is immerfd 
in a cii^ern iA fiill of cold water, and it is con- 
trived fo as to expofe a very great furfacc cxttrnallj' 
to the water, and internally to the fleanru It is alfo 
made air-tight, and has pumps N wrought by die 
engine, which keep it always exhaufted of air and 

Both the cylinders A and BB being filled widi 
fteam, the paflage K is opened from the inner one 
to the condenfer i , into which the fteam vioieof/y 
ruflies by its claftirity, becaufe that veflel is cx- 
hauftcdi but as foon as it enters it, coming into 
contaft with the cold matter of the condenfer, it is 
reduced to water, and the vacuum ftill remaining, 
the fteam continues to ru(h in till the inner cylinder 
A below the pifton is left empty. The fteam whidi 
is above the pifton, cfeafing to be countcradcd by 
that which is below it, adts upon the pifton HH, 
and forces it to defcend to the bottom of the cylin- 
der and fo raifes the bucket of the pump by means 
of the lever. The paflage K between the inner cy- 
linder and the condenfer is then fliut, and anothtf 
paflage O is opened^ which permits the fteam ^ 
pafs from the outer cylinder, or from the boikr 
into the inner cylinder under the pifton \ and then 
the fupcrior weight of the bucket and pump rods 


" p. 444. 

Plate 4. 


Ch^p; I.] Heater in the State of Ue% 445 

pulls down the outer end of the lever or great beam,^ 
and raifcs'the pifton, which is fulpended to the 
inner end of the fame beam. 

When water is expofed to a cold atmofphcre, it 
firft lofes its free caloric, and is reduced in tempera^i 
tore, but no part of it begins to freeze till the mafs is 
reduced fomewhat below the thirty- fccond degree of 
Fahrenheit's thermometer; a fmall quantity of the 
water then becomes folid, which, by changing its ftate, 
fets at liberty a quantity of its combined heat, which 
reftores the water in contact with it to the tempe- 
rature of 32 degrees, or rather above it. The con- 
gelation is therefore at a ftand till this fcnfible heat 
is abftraded by the atmofphere, and the mafs again 
reduced fomewhat below the thirty-fecond degree. 
Another portion of water then congeals, and the pro- 
cefs is again Hopped by the emiffion of heat. In this 
manner congelation pervades the whole mafs, and 
is performed at intervals, which are very obfervablc 
when the phenpnienon of freezing is accurately at- 
tended to. 

The lacne law operates in the pafTagc of other, 
bodies from the (late of fluids to that of folids, and 
the contrary. Dr. Irvine has fhewn, that, when fper- 
maceti and wax are melted, they contain heat in a 
combined or latent ftare. By heating them much 
above their point of fluidity, he found that they loft 
their heat very foon, till fomc parts became folid 5 
after this they continued of exaftly the fame tem- 
. pcrature till the whole became folid, though expof-. 
ed all the while to cold air ; but when all became 
folid they cooled as they did at firft. In the fame 


44^ Water in the State of tee. [Bopk Vlt. 

manner water mixed with Icc^i wh^tev^r may be the 
leiTiperature of the furrounding medium, and whe- 
ther thequantity of ice isincreafing or diminiHun^ 
always nearly preferves the temperature of 32 de- 

The freeing of water was formerly attributed to 
the entrance of frigorific particles into that fluid i but 
the above doftrine, founded on the great difcoveries 
of Dr. Black, is almoft univerfally deemed fo fatisfac^ 
tory as to have left the other, which is a mere hy- 
pothefis, fcarcely a finglc advocate- The augmen- 
tation of the bulk of water in freezing fecms to be 
the only faft which can with reafon be alledged 
in fupport of the dodbrine of frigorific particles } 
but this increafe of bulk is not attended with any 
increafe of weight, and may be much better ex- 
plained, than by attributing it to the addition of 
frigorific particles, which were never proved to 
have any exiftence. 

The increafe which water acquires in becoming 
fbtidis about one-ninth or one-tenth of its whole bulk: 
Boyle took a brafs tube, three inches in diameter^ 
and put fome water into it; he then brought down 
into the tube a plug with a weight placed at the 
head of it of fcventy-four pounds. On expofing 
the tube to the cold, the water freezing and expand^ 
Jhg itfclf, raifed the feventy-four pounds. The ex- 
panfive power of water, in the procefs of freezing, 
was proved by a remarkable experiment made in 
Canada. An iron fhell, after having its moutb. 
well plugged up, was filled up with water and ejt- 
pofed to a fevere froft which prevailed in thai 
I country. 

Chap* I .] Esfftttjfivi ^m&. of Fr^. 44^ 

country* The cxpaafion pf the ice farced put the 

plug, and the water, which imnpcdiatdy foUowcct 

was frozen into an irregulajr ixiafs or cojumn of ice. 

The in.ffancesi, however, already mentioned, are far 

lefs ftrjking than one defcribed by Mufchen$roeck, 

in which a ball of iron, ^n inch thick, was burft 

afunder in the courfe of twelve hours by the ez- 

panfive power of frolt That philofopher having 

calculated the force exerted by the freezing of wate^* 

in a fimilar cafe, found it equal to a force capable of 

raifing a weight of twenty-feven thoufand fcven hun- 

« dred and twenty pounds. That the expaijC ve power 

pf freezing water, howerer, has certain limits, appears 

frooi thefoUowing experiment, made by the Floren* 

pnc academicians. A brais globe filled with water, 

and clofed at its orifice by a well-fitted fcrew, wa$ 

immerfed in freezing water, but did not burft ^ they 

then pared off fuch a quantity of the metal as left rhe 

fides of the globe unable to refift the expanfion of 

the water J the force which v^as required to burft 

the globe in this ftate was computed at twenty-fcyen 

^houfand pounds. When fuch is the expanfivc 

power cxqrtcd by water in paffing to the ftate of ice, 

we c^nr^ot be furprized that veflcls, which are left 

fiU^d with water in frofty weather, ftiould be burft by 

its freezing, and that the fame tiding fhould happen 

to water-pipes cxpoftd to the aftion of froft. The 

pavement is fometimes loolened froip th^ fame 

caufe, ^nd in cpuntrics wJ\erc very fcvcre pplds prc- 

vailj the fap of trees qongcals, and their trunks ar^ 

burft afunder with a noifc like that of cannon. 


44^ Phenomenon at Mo/cow. [Bo6k VIL 

rroft fertilizes the ground, by loofcning the cohe- 
fion of the particles of earth. 

As ice is never perfedly clear or tranfparent^ aiKi 
as we find fmall cavities in it, fome have chdu^ 
that the air infinuates iclelf; but this has been refuted 
by water being frozen under an exhauftcd receiver, 
and the fame cavities being found m the ice. The 
ice, in fa6l, inftead of being heavier, was found to 
be lighter. The expanfion of ice. Indeed, is evi- 
dently owing to the cryftallization of the water, and 
the particles affuming a different arrangement, and 
not being in clofc contaft. If this is admitted, as 
I apprehend it muft, we cannot fay, with propriety^ 
that the folid particles of water expand. The Ipi- 
cute, of which ice confifts, cut each other at angles 
of lixty or one hundred and twenty degrees. 

When it fnows at Mofcow, and the air is not too 
dry, it is obferved to be loaded with beaudfut 
crydallizations, regularly flattened, and as thin as a 
leaf of paper. They confift of an union of Bbrcs, 
which Ihoot from the center to form fix principal 
rays, which arc themfelves divided into extremely 
fmall blades. 

It appears, however, that the air previoufly con- 
tained in water is fet at liberty on the congeladon 
of that fluid, and ifeay thus partly contribute to the 
fwclHng of ice, and occafion fome of the cavities _ 
obferv^le in it. 

W hen water freezes flowly, its furface prefcrves its 
tranfparency to fo:r.e depth, owing to the air which 
is feparated pafling downwards as the freezing pro- 
ceeds. The air bubbles, however, foon begin to 


Ctep. I.] PheHomeHa ofPreezing. 449 

coUcft, and produce confiderablc inequalities, which 
increafe as they approach the center. When, on 
the contrary, water is frozen With great rapidity, 
the bubbles of air difperfe themfelves pretty equally 
through the mals, which, in confeqiiedce, becomes 
opake through its whole fubftance. 

Reaumur obferves that caft iron melted, in pair- 
ing from a fluid to its folid ftate, expands. This 
cfFeft is more fenfible in this than in any other, of 
the metals, on account of its platey texture. He 
found that caft iron, thrown among fome of the 
fame metal melted, fwims upon the top. In the 
cafe of immediate expanfion upon congealing, the 
iron fcems to agree with water: they differ in this j 
the iron never expands by cold afterwards, whereas 
the ice, being expofed to greater degrees of cold, 
becomes more bulky -, the folid parts not being fo 
clofely conneSed from a particular arrangement, 
which renders the whole mafs lighter thah biefore. 
Quickfilver contrafts in becoming folid j and both 
caft iron and ice contain ftveral interftices, which. 
If allowed for, make it appear that thefe bodies in 
reality occupy lefs fpace when folid; than in a fluid 

Vol. ir. G g € h a p. 

I 450 ] [BookVlL 

C H A P. 11. 

Hydrostatics. . 

Di/con/eries of Arcbimedis in this Branch of Sciena^^^Of the hlo^ 
derns.^^Ho'w Fluids are aSled upon by the general Larjus of Gra- 
'Vitatibn.^-^P articles of Fluids a3 independently of each other.*^ ' 
Efcperiment afcertaining this Principle. '^Fluids prefs efttally in all 
DireSions, '•^Cautions necejjary in.conftru^ingjSquedudSg t^c. to 
guard againfi the lateral Prejure of Fluids,"^ All Parts of the 
fame Fluid in Equilibrium luith each othtr,^^Surfaces cf Fluids 
always in a Plane parallel luith *the Horixjon^^^P rejjure of 
Fluids in proportion to their Height, "^Hydroftatic Paradox.^ 
EffeBs of Gravity on Fluids of different Denfities* — A£lioM if 
Air- on the Surfaces of Fluids,-^The Siphon,'^AclioH of Fluids 
onfolid Bodies immerfed in them.^^Why certain Bodies fsnk and 
others f-wim in certain Fluids,^^ Bodies that fwim difplace m 
Bulk of Waieir equal to themfel*ves in Weight but nH in Magui' 
tude.'-^The fame Body luilljink in one Fluid, ivhicb ivillfivim 
in another ^"-'The Hydrometer,~^Fahrenheii' s Hydrometer, ^Rt* 
capitulation of the Do^rines refpeSling JPecifc Gravity, — How 
to make a Globe of Ironf^im on the Surface of fTaten^^BMls 
made of Copper, ' 

WATERy as a fluid, has certain properties, 
which, though common to all unelaflic or 
incompreflible fluids, arc ufually confidered under 
this topic ; and indeed the fcienccs of hydroftatics 
and hydraulics, which regard thefe properties, im- 
mediately derive their names from that fluid •> od 

* *r^u^ (Hydor) wsiter, and erlal^xfi ((btike) the fcience of 
weight. Hydraulics from 'y^$ ^^^ «vXo{ (aalos) a tube or pipe. 


Chaj). 2.] Hijcam^ry af Archimedes. 45 i 

V^hich the experiments, illuftrativc of them, are 
ufually made. 

Hydroftatics have for their objedt the weight 
and prefllirc of fluids; and in this branch of 
fcience the art of determining the fpeqific gravi- 
ties of bodies is ufually included, but this I jjave 
already been under a neceflTuy of anticipating * in 
fome degree. ArchimedeSy among the ancients^ 
accompliihed the moft remarkable difcovcrics iri 
this fcience. He is honoured even at this day, as 
the invcnter of the ingenious hydroftatic procels^ by 
which the purity or bafenefs of a crown of gold 
was afcertained. Among the moderns we are in- 
debted to Gallileo, Torricellii Dcfcartes, Pafcalj 
Guglklmini, and Mariottc, for the beft informadort 
on this fubjeft ; and by their experiments (which 
are as curious as they are decifive) we are inftrufted. 
in what we may cxpeftor fear from the power of 
fluids violendy adled upon by the principle of 
gravity, and in what manner and lipon what prin-* 
ciples we may employ, for the ufe of mani the hy- 
draulic machines. 

It has, been obferved in another place, that the 
propcnfity which bodies have of approaching to- 
wards the earth, or perhaps towards its center, is 
the only caufc of what we term weight, or gravity, 
and that it is by the continual efforts which they 

* See Book L Ghap. III. It was nece/Tary to explain the 
nature of fpeciiic gravity in that part of the work, both becaufe 
it relates rather to bodies in general than to fluid fubflances ; 
and becaufe the frequent alluiions to it in the progrefs of the 
work would not have beenjotherwiie underftood. 

G g 2 mfke 

45^ . Particles of Fbdds. [6ook VIL 

make to obey that law, that they prels upon every 
obftacle which impedes their progref^. As fluid9» 
like folid bodies, are impelled by their gravity, fb 
in this cafe they prcfs upon every objeft which 
opi ofes their fall ; but from their nature they 
prei^ in a different manner fi-om folid bodies; 
hence arife the peculiar phenomena into which we 
are now to inquire. 

Fluids are fubftances, the component parts of 
which are moveable among themfelves, having 
fcarcely any cohefion one with another, and moving 
independently of each other. Some philofophers * 
have included in this definition wliat they term^ die 
grofler fluids, as, for example, a heap of com, a 
heap of Ihor, of fand, &c. as well as the rarer and 
more elaftic fluids, as common'air, and all other 
aeriform fubftances. The proper obje6Ls, how- 
ever, of the hydroftatic fcience, arc thoft fluids 
which, in common language, are termed liquids> 
or thofe which always prefent to us a plane fur&cei 
level or parallel to the horizon. 

All liquid fubftances are not equally i^o ; hence it 
follows, chat the laws of hydroftatics apply with 
Icfs exaftnefs in proportion as thofe fubftances de- 
part from perfeft fluidity. Water and oil both 
flow when the veflels, which contain them, are 
cither overturned or broken; but theeffufion of 
oil is flower than that of water, becaufe the par- 
ticles of oil have more cohefion among themlclvcs. 
The moft Angular effefts iq hydroftatics princi* 

• See Briffon, VoL L p. 23.3. 

Chap. 2.] Principles of Hydrojiatics. 453 

pally depend upon the extreme minutenefs of the 
particles of fluids, and upon their great mobility. 

To preferve a lucid order in the confideration of 
this fubjcft, it will be neceflary to divide the objeAs 
of our inquiry into three branches. In the firft 
place, therefore, I (hall confider in what nnanner 
the principle of gravity afts on the particles of 
fluids, and the phenomena which it produces in the 
fluids themfelves ; as well as their z&Xon againft 
the fides, the bottoms, and tops of the veffels in 
which they are contained. Secondly, I (hall con- 
fider in what manner fluids of different denfities 
aft upon each others and thirdly, the aftion of 
fluids on bodies immcrfed in them. 

I. In purfuing the firft objcft of this inquiry, it 
may be eftablifhed as an. axiom : 

ift, That the parts of the fame fluid aft with 
refpcft to their weight or preflTure, independently of 
each other. 

This property arifes from their having fcarcely 
any cohcfion among themfelves. It is orhcrwife 
with folid bodies j their feveral parts adhering to- 
gether, they prefs in one common mafs ; hence the 
falling of folid bodies is produftive of a different 
effcft from that of liquids. We dread the falling 
of a pound of ice upon our heads, while we are 
much more indifferent concerning that of a pound 
of water. The latter, in its defcent, is divided 
by the refiftance of the air, by which fome of 
its parts are retarded more than others; ard the 
fwiftnefs of the whole mafs is ftill more retarded 
by this divifion than it otherwile would be; for by 

G g 3 being 

4S4 Particks of Fluids off indepenckntfy [Book VII. 

being thus divided it acquires a larger furfacc, 
wl?ich abates its cflfedf. On the contrary, a folid 
body fells upon a fmall fpace, which receives its 
whole force. Hence it follows, that angular bodies 
falling upon any part of the human frame are more 
dangerous than flat or plane ones of the fame 
weight, and defcending from the fame height. 

It follows from this principle, that if an apemjrt 
IS made at the bottom of a veflel full of any fluid, 
in order to prevent the flowing out of the liquor, 
it is only ncccflary to counteraft the weight of that 
column of fluid which has the aperture for its'bafe, 
and that to counteraft that weight it is the fame 
whether the veflel is full of liquor, or whether it 
contains only a column, the bafe of which Ihall be 
equal to the aperture at the bottom. 

Let the cylindrical Veflfel of glafe A B (plate V. 
fig. I.) have a hole in the bottom at C, fbrnilhcd 
with a cylindrical ferule of copper of an inch 
diameter D, which is to be fliopped with a pifton 
G> or the fucker of a pump well fitted to the feru/e, 
and oiled, that it may yield to a moderate preflure. 
Let the pifton be fiipported by a fmall rod G H, 
faftened at H to the filk which unices with the por- 
tion of the pulley M, with which the extremity of 
the lever M N is fiirniflied, and which has for its 
center of motion the point L. The other portion 
of the pulley N, which terminates the other cx- 
tfenriity of the lever, is alfo furniflied with lines of 
filk, which fupporc the fmall bafon or fcalc I 
Xlpon the copper ferule D then fit a cylindrical 
tube of gla& FE, the interior diameter of which 

Chap. 2.] of each ether as to Weight arPreJfure. 455 

is equal to that of the ferule> and its height 
equal to that of the veflel AB. When the 
apparatus is difpofed in this manner, fill the tube 
E F with water, and continue to put fmall weights 
in!b the bafon or fcale I, until the pifton begins to 
rife. Afterwards take away the glafe tube E F, and 
place the pifton G in the copper ferule D, and pour 
water into the large velTel A B, and it will appear 
that the fame weights as before in the bafon I, will 
raife up the pifton when the larger vclfel A B is 
entirely full. Hence it follows that there is the 
fame power to be cpunterafted, whether there refts 
upon the pifton only a column of water of its own 
fize, or whether the vcffel- A B is entirely fulU 
Such a column, therefore, preffes upon its bafe in- 
dependently of the reft of the water contained in 
the veflel. 

To account for this, let us fuppofe all the water 
in a veflel to be divided into feveral columns, i, 2, 
3> 4> 5i (plate V. fig. 2.) each compofed of an 
equal number of parts. If the bottom of the vef- 
fcl, which ferves for the bafe and fupport of all the 
columns, is opened in a, the column 3, being no 
.longer fupportcd, will defcend through the aperture, 
fliding between the two columns 2 and 4, which 
are ' fupported by the parts of the bottom of the 
veflel b and f, all the moveable parts of which 
become (if I may ufe the exprefllon) fmall rqllers, 
which retard the fall Only in a very flight degree. 
This eflTed is the rcfult of the fmall, degree of co- 
hefion between the parts of the fluid. If the co- 
lumns I and 2 on the one part, and 4 and 5 on the 

G g 4 other, 

45^ Particles of Fluids have no Cobejion. £Book VIL 

other, were compofed of parts adhering togethcct 
they would retard each other in their defcent dwr- 
ing their whole length, in the fanne manner as a wax 
candle would doi and by the fall of the cplunnn j, 
a void would be made between them, Bqt as all ihc 
particles arc extreniely minute, moving cafily u|x>n 
each other, they defcend when the funjmit of the 
column 3 begins to defcend, having no longer any 
fupport from that fide ; and the foperficics of the 
whole mafs defcends in the fame manner, though 
only one of the columns caufed the flow from its 
fall. When the pares have a degree of vifcoficy, as 
thofe of oily fluids, or when the mafs of the flow- 
ing liquor has much more of breadth than of 
height, the void which tTie defccnd^lng colunin 
leaves above it is eafily perceived, for then the fur- 
face, infl:ead of being plane -and even, is hollow in 
the middle, and aflumcs a funnel-like form, becaufe 
the adjacent parts do not arrive with fuffidient fwift. 
nels to replace thofe which defcend through the 
aperture ; befides the preffure of the air above the 
aperture is ftron;::cr than its refiftance below. 

From what has been now ftated, it is cafy to per- 
ceivc how fluids diflfer from folids in the phenomena 
of gravitation. If the veflel A B (plate V. fig- i.) 
being full of water, and the tube E F toeing re- 
moved, it was required to raife up the pifton G ; 
all that is neceffary in this cafe is, ro fupport the 
weight of the column of water direftly above the 
pifton, becaufe this column can move independently 
of the remainder ; but if the whole mafs of water 
was converted into ice, then the mafs ceasing tr 
" ... ^^ 

<E{iap. iJ] Fluids prefs equally in all DireSions. 4 jy 

be a liquid, and all Its parts adhering together, to 
raifc up the pifton it wQuld be neceflary to fupport 
the weight of the whole mals. 

adly, Fluids prefs equally in all djredjtioijs. 

In other words, they not only prefs from the 
top. to the bottom like other bodies, but they alfo 
prefs, according to their weight, upon all bodies 
that oppofe them in a lateral direftion, and even 
from the bottorn to the top. Hence, if a calk is filled 
with liquid oil, the oil will run out if an aperture is 
made in the fide, but when it is congealed it will 
pot run out, on account of its having become a 
folid body, for folid bodies prefs only from their 
vertex to their bafe, and not laterally. 

To undcrftand properly this lateral preffurc of 
fluids, and alfo that which they exert from their 
J)afe towards their vertex, it is neceflary to confider 
them as a mafs of fmall globule^ depofited in a vef. 
fi-1 ; and to remember that thefe minute globules 
are not arranged regularly as upon a cord, but that 
ycry frequently one column exercifes its preflTurc 
jDctween two others, and has a propoifity to dif- 
pliice them, as may be feen in plate V. (fig. 3.) 
where the perpendicular preflure which is made 
oppofite to the point d, is diredted by the lateral 
columns towards the fides, ^ /, of the veflel, in fuch 
a manner, that if the veflel was open in thofe 
places the liquid would flow out, on account of the 
great mobility of its parts. It is by the fame mode 
ofreafoning that the preflTure of fluids, from their 
^fe* towards their vertex, is accounted for: for 
example, when the column df (fig. 3.) has a ten- 

458 Caution with reJ^tSitoAqutduSSy^c. [Book VIL 

dency to difplace the two particles g hy the particle 
g cannot move any farther becaufc it is impeded 
by the fide of the veflel j but the particle b may be 
raifed from the baft towards the top, unlefs a 
column equal to the column i ky or ibmethii^ 
equivalent, prelTes upon it to prevent it. 

It is upon this principle that the water, elevated 
by the New River water-works, after having de- 
fcended from a bafon in a vertical pipe, and then 
after having AowclV horizontally in a fucceflion of 
pipes under the pavement, is raiftd up again, through 
another pipe, as high as the fountain at the Temple 
Garden. It is alfo upon this principle that a veflel 
may be filled either at the mouth or at the bottom 
indifferently, provided that it is done through a 
pipe, the top of which is as high as the top of the 
veflel to be filled. Hence it follows, that when 
piers, aquedufts, refer voirs, or other hydraulic 
works for the retention of water are to be con- 
fl:ru6bcd, it becomes neceflary to proportion their 
ftrcngth to the lateral prefllire which they are likely 
to fuftain, which becomes greater as the height of 
the water is more confiderablc. Nearly the fame 
precautions are neceflary to be taken with refpeft 
to what Tome philofophers call the groflfer fluids, 
which alfo have a propenfity to expand, as well on 
account of the fmallnefs of their parts as from the 
fmall degree of cohefion which . cxifts between 
them. Walls defigned to fupport terrafles ought to 
be fufficiently ftrong to refift the lateral prefliJrc of 
the earth and rubbifli v^hich they are to fuftain, 
as this preflbre will be greater as the particles of 


iGhap. 2.] Particles in Equilibrium. 4551 

jearth, and of the other materials of which the ter- 
rafles are compofed, are Icfs bound together, and in 
proportion as the terraffes arc more elevated. 

3dly, All the parts of the fame fluid are in 
Cquilibriym with each other, whether they arc 
contained in one veflcl of many, provided they 
communicate with each others and their furfaces 
alfo are always in a plane parallel to the horizon. 

This is a confequence of the principle which has 
been before eftablilhed : for, iince the particle b 
(fig. 3.) would be raifed from the bafe towards the 
top, unleft a column equal to the column ; ky prefled 
upon it to retain it in its place ; it follows that to be 
in equilibrium, the upper extremities of the two 
columns Ihould be in the fame horizontal plane, 
or in points equally diftant from the center of the 
earth j which points, however, cannot be found by 
a right line ; for in the diftance of a thoufand fa- 
thorrrs there is about one foot difFefencc in the per- 
pendicular height. From this property of fluids 
it follows, that water condufted by pipes placed 
in the eanh, will remount as high as the place 
whence it flowed, whatever the depth under 
ground through which it may have been conduct- 
ed by pipes. It is cuftomary to allow half an inch 
of inclination in the length of fix feet, to counteraft 
the refiftance produced by friftion 5 but it is clear, 
from what has been faid, that this is not abfo- 
iutely necefiary, for however long the paflagc 
might be, the water would ftill afcend as high a^ 
the place whence it came, but it would require a 
little longer time to accomplilh the afcent. Wtf 


460 springs on the ^ops of Mountams. [Book VIL 

arc enabled, upon this principle, to account for the 
Iprings wnich are fonDctimes found on the tops of 
mountains. Such waiters flow from mountains 
ftill more elevated (whether they are far or near) 
by fubterraneous canals. It foUow§ from this prin- 
ciple, that if there are many refervoirs which com- 
municate together, it is neccflaiy only to (ire one 
of them to know the height of the water in the 
others \ for it muft neceffarily he of the fame height 
there as in all the reft. 

From what has been obfcrv^d, viz. that when all 
the parts of the Cime fluid are in equilibrium, their 
furfaces will alfo be in a plane parallel to the hori- 
zon, or, in other words, evay part of the fur- 
face at an equal diftance from the center of the 
earth, it follows, that when the furface of water is 
very large, it becomes neccflarily and fcnfibly con- 
vex. This is eafily perceived at lea, where the 
mafts of (hips are obferved at a diftance before any 
other part of the ftiip can be diftinguilhed. 

4thlyj, Fluids prefs as well perpendicularly as la- 
terally, npt, however, in proportipn to their quan- 
tity, but in proportion to their height above the 
plane of the horizon. 

For example, if feveral vefiels of the fame hei^t 
and bafc are filled with water, all their bottoms 
will bear the fame degree of preffure, whatever may 
be the form and fizc of the veflels in other refpeds. 
Suppofe three veflels to be filled with water, 
ABCD (fig. 4.) EFGH (fig. 5.) LMNQ 
PQ^(fig-6.) whofe height? A B, IF, LTarc 
equal, and alfo fupported by equal bafes B C, FG, 


Chap. 2.] Fluids prefs in Proportion to Height. 461 

N O ; it will be found, by experiment, that all the 
bottoms of thefe veflels will be equally prefled, though 
t\\L quantities of water which they contain may be 
ver*' different. In the veffcl (fig. 4.) the bottom 
B C is preffcd by the whole mafs of water AB C D, 
becaufe the fluid, in this cafe, preffes in the fame 
manner as a folid body ; let us fuppofe the weight 
of the water to be fix pounds : In the veflcl 
(fig. 5^) it is eafy to conceive, from what has been 
faid before, that the bottom FG is alfo only 
prcffed by fix pounds, though the vefTel is evi- 
dently much larger than the firft j becaufe the bot- 
tom F G fupports only the column I F G K, equal 
to that of the veffel (fig. 4.) and this column exer- 
cifes its preffure independently of the refidue of the 
water in the veffel, which is fupported by the fides, 
E F, H G, of the veffel (fig. 5.) But the princi- 
pal difficulty confifl:s in comprehending how the 
bottom of the veffel N O is ftill prcffed by a weight 
of fix pounds, although one pound of water would 
be fufficicnt to fill the veffel. It is accounted for 
in this manner ; it is certain that upon the ponion 
T V of the bottom N O, there is a preffure equal 
to that of a column of water of which TV is the 
bafe, and L T the height. If, upon every other 
fimilar portion of the fame bottom, there is a pref- 
fure equal ^to that of the column LTV Q, the 
bottb(n is equally prefled upon all its parts. For 
inftance, there is a preffure upon the portion V X 
equal to that of a column of water QV X R, 
which is itfelf equal to the column LT V Qj for 
the fmall column of water P V X S, which refts 


46^ .. Hydrojiatic ParaJox. [Book VII 

^bowt^ naa a propcnfity to be elevated by the pref- 
fure of the adjacent column LTV Q, and with a 
force equal to the excefs LMPQ^of.this grot 
column over the fmall one ; therefore Ifcc upper 
partj PS, is prefled by the fame power; but the 
rc-a6kion is equal to die preflure. The part P S 
re-afts with a force equal to the excefs L M P Q^ 
of the great column over the (mall one. There 
is, therefore, a preflure upon the portion VX 
9f the bottom N O, from the fmall column of 
tMCer P V X S, and from the re-adion of the part 
1^ S, equal to the preflure of a column of water, 
QJ* S R> both of which added together are equai 
to the prcfllire of the column L T V Q^ What 
has been faid of the portion V X may be faid of all 
the reft. Hence it foUov's that the bottom of the 
veflel (fig. 6.) is every where equally prefled. 

There is a maxim deduced from what has been 
ftated, which is termed by philofophers the bydro- 
ftatic paradox ; it is nev^rthelcfs founded upoji the 
fureft bafis of truth, and has a confiderable influ- 
ence in almoft all hydraulic engines, viz, " that a 
given quaniity of water may exeh a force two or 
three hundred times lefs or greater, according to 
the manner in which it is employed." If, for in- 
ftance, the fame quantity of water as the veffd 
(fig. 5.) will contain, is poured into a vcflcI rc- 
fembling that of (fig. 6.) but high enough to con- 
tain it, the preflTure upon the bottom NO will be 
confiderably greater than that upon the bottom FG» 

One of the mofl: ufeful machines to flicw that a • 
finall quantity of water is capable of great prdTu/ti 




► ♦ # ♦ 4 ^ 

^ 4 ♦ 4 4 ^ 
k^ ^ ^ 4 4. *l 

^ ^ 4 4 4 ^1 
^ 4 4^ # 4 ^ 
. 4 4 ^ 4 ^ 

^^ J 

^^ ^ 



Chap, 2.] Hydrofiatic Bellows. 463 

is the hydroftatic bellows. This machine (Plate VI. 
fig. I.) confifts of two thick oval boards, each 
about three feet broad, and four feet long, united 
to each other hy leather, like a pair of<ommon bel- 
lows, or a barber's puff. Into the lower board a 
pipe B, feveral feet high is fixed at e. Now, in fhew- 
ing experiments with this fimple machine, which 
even the reader himfelf might eafily make, let water 
' be poured into rhc pipe at its top C, which will run 
into the bellows, and feparate the boards a little: 
then to fhew how much a little water will be able 
to effe6t by prcffure, let three weights, each of an 
hundred pounds, be laid upon the upper board. 
Now if we pour more water into the pipe, it will 
as before run into the bellows, and raife up the board 
with all the weights upon it. And though the 
water in the tube fhoukl weigh in all but a fingle 
pound, yet the preffure of this fmall force upon the 
water below in the bellows, (hall fuppprt the 
weights, which are three hundred pounds i nor will 
they have weight enough to make them defcend, 
and conquer the weight of the water, by forcing it 
out of the mouth of the pipe. 

It is clear from thefe principles, that the tua 
TO (fig. a.) filled with water, may be burft by 
prefling it with fome pounds additional weight of 
the fluid, through the tube A B, which may be fup- 
pofed to be from twenty-five to tliirty feet in 
height. From what has been faid of the veflel 
(fig. 6.) it indeed neceffarily follows, that the fmall 
quantity of water which the tube A B conuins, 
preiTes upon the bottom of the tun as much as if a 


4^4 i^fff^s of Gravity tm Fluids [^ook V iL 

column of water had been added as wide as the 
ttin itfe]f> and as long as the tube^ which would 
cvid^ndy be an enormous weight. 

II. The effcfts of gravity on fluids of different 
denfities will, frorti what has preceded, rioc be very 
difficult to comprehend. 

It has been obfervcd, that fluids arc mafles of 
fmall bodies moveable with great facility among 
themfclves independendy of each other, prcfling 
fcparately and in proportion to their maflfes. 

It is proved alfo by chemical analyfis, that even 
thefe minute particles ire c^ompofed of particles ffiH 
fmaller. Now whether it refults from the intcrpo- 
fition of caloric (or the matter of fire) in greater dr 
lefs quantiricg, which we know is the caufc of all 
fluidity, and alfo of the difference that cxifts between 
the incomprclTible and elaftic fluids; or whether it 
may depend upon the fliape or fize of the particles, 
which, as in folid bodies, may increafe or diminKh 
the porofity, it is certain, that there is a confidcr- 
able diflfcrence with refpeft to denfity in diflfcrent 

From this difference in point of denfity, a lepa- 
ration may be obferved generally to take place, 
foon after mixing two heterDgeneous fluids toge- 
ther, unlefs this effc6b is counteraAed by fome more 
powerful caufe. It has been obferved, that the 
particles, according to their weight, prefs indepen- 
dently of each other. Thofe therefore which 
have the moft denfity, having more power to gaki 
poflfeflion of the lower part of the veflcl which con- 
uins them, oblige the odiers to yield and refign 


Chap. 2. J tjf. different DenJitUs. 465 

their Atuation ; and hence a fcparation is efFefted. 
When oil and water, for inftance, have been well 
fhakea together, and afterwards the whole left in a 
ftate of reft, the water, having more denfity than 
the oil, takes the lower pofition j^nd the oil rifes to 
the furface. If this effeft does not take place, it is 
owing to the intervention of one of the following 
caufes. Firft, a kind of elefliive attraftion, which 
may exift between the particles of different fluids, 
as when water and wine are mixed together, the 
water, though heavier than the wine, does not fe- 
parate itfclf. Secondly, the vifcofity of one of the 
fubftances, as when the whites of eggs are beaten 
together, and by that means a confiderable quan- 
tity of air' mixes with them i the air, though much 
lighter, has not power to difengage itfelf from the 
inatter in which it is enveloped, in order to effeft 
its efcape. 

If two fluids of different denfities are placed in a 
ftate of equipoife with each other, and have the 
fame bafe, their perpendicular heights above the 
horizon will be in a reciprocal ratio to their denfi- 
ties or fpecific gravities. 

/ If, for example, mercury is put into an inverted 
fiphon, and water is poured into one of the branches, 
'in order to elevate the mercury in the other branch 
one inch above its level, it is neceflary that the 
water ftiould be about thirteen inches and an 
half high. The height of the water then will be 
•thirteen times and a half of that of the mercury; 
bccaufc the ipecific gravity of mercury is about 
Vol. II. H h thirteen 

466 Prejfuri of ihi Air uf on Fluids. [Book VII. 

thirteen times and a half as great as that of 

This obfervation will alfo apply to the reciprocal 
aftion of air and water, or air and mercury upoo 
each other, as was evinced in a former book^ 
when treating of the Torricellian cxpcrinacnt and 
the barometer *. Many of the phenomena, indeed^ 
of hydroftatics and hydraulics are to be referred to 
the preflbre of the atmolphere,, and for this rcafbn, 
,thc prefent fubjeft has been in part anticipa&edt 
when it was neceflary to treat of air as a fluid. 

It is, however, proper on the prefent occation^ 
to recal to the reader's attention fome of the pro- 
perties of this fluid, and he will eafily remember, 
that as a fluid, air is pofltfled of gravity, and con- 
fequently preflTes upon all bodies which oppofe itj 
and it is neceflfary to add, that Tike water, it prefles 
in all diredtions. Its perpendicular prefTure has 
been already fufEciently proved} and its lateral 
preflbre may alfo be eafily dcmonftrated. If a 
fmall hole is made with a gimblet, either inihe fide 
or bottom of a caflc or veflfel which is quite full of 
liquor, it will not run out, becaufe the external air 
which prefles againfl: the hole, fuftains the liquor, 
which has not a fufficient height to overcome its 
prefTure. Hence the necelEty of a vent-peg, to 
enable liquor to be drawn out of a full caflc. The 
.clafl:icity of the fmall quantity of air which is intro* 
duced at the vent preflTes the fluid, and bvercomci 
theprcflTure of the air at the cock. There is ao 

^ See Book v. Chap. 9, 


Chap. 2; j ^he Siphon. aJ^J 

tnftrument in common ufe, called a Valencia, fof 
extracting fmall quantities of liquor out of the biing- 
Holes of cafks. It' is a tub* with* a fnriall aperture ^t 
the bottom ind the top. When fdll; if thfe hole at 
th6 top is ftopjied with the thumb or finger, fo as rcJ 
prevent the prefllire of the air at the top, the liquor 
will not run but of the hole at the bottom; being 
kept: in By the force of the fcxterrtal air. 

It IS proper to obfcrtfe, that all the effefts which 
depend upo.ii the preflTure of air; take place m i 
\oovci where the column of air is terminated by the 
ceiling; as well as without doors where the columri 
bf air has the whole height of the atmofjihere- arid, 
the reafon is, becaufc the air in the room has i 
communicadori with that on the dtitfide, fuppofing 
It to be only by rheans of the key -hole, Thiis a 
barometer placed in a hall, will have its mercury 
as high as if it was placed in an opfen field. 

The cijrious efFefts produced by fiphons, all 
dcpend'upoh the preflure of the air. 

A fiphon is a bent tube ABC (fig. 3), made oif 
'glafsj of metal, or bf wood. One branch of Which 
A B> is fhortcr than the other B C; In order to maki 
ufe of this inftrument, place the extremity of the 
fhort branch A B in the veflcl E E; (fig: 4.) which 
may be fiippofed to contairi any fluid riiatter, ai 
\vatcr for inftance. If the air theh is dtawn by fuc- 
tion * out of the fiphon at the extremity C of the lori^ 

• S(i6lion Is here evidently ufcd ill the popular fenfc of the 
Word, to iiilply that aftioii 6{ the moath which extracts the 
air from a given fpace: for in ftrid philofophical language 
there is no fach thing* 

H h a branch 

468 fbe- Sipbcn.. [Book VIL 

branch B C, the liquor will begin to flow, and will 
not ceafe while the fhort branch A B remains im- 
merfed in the fluid. It is eafy to fee that the pref- 
fure of the air upon the furface of the fluid in die 
veflel, is the caufe of its difcharge through the fi- 
phon. For fuppofe G F the confines of the atmo* 
iphere, all the points of the furface A of the liquor 
will be equally preffcd by the column of air A F ; 
if, therefore, at fome point of this furfece, the 
preflure is fulpended, the liquor m6ft flow at that 
point, becaufe it finds lefs refiilance there than in 
any other part ; this is therefore the obvious reaibn 
why the fiphon, becomes full immediately after the 
air is drawn out at the extremity C. 

If the two branches of the fiphon were of equal 
lengths, as B A> B D, the flow through the bent 
tube would not take place; becaufe the column of 
air D G which would rcfift in D, being of an equal 
height with that which preflfes at A, would alio be in 
equilibrium with it, in the fame manner as the two 
columns of the fluid B A, B D, But fmce B C, 
one of the legs, is longer than the other, though the 
column of air G C, which anfwers to it, is really 
longer than that which prefles in A ; yet it is not 
capable of preveiving the paflage of the fluid. To 
underftand this more perfedlly, let us confider the 
column of air G C to be divided into two parts, one 
of which, G D, would form an equipoife with the 
column of air;F A, and would be capable df ftop- 
pihg the flow from the tube if the branch B C end- 
ed in D. The portion of fluid which fills the pait 
I) C of the fiphon, will find no other refiftance in 


Chap, a.] AEtion of Fluids on JoMBoJies. 46^ , 

C than one column of air D C of the fame. length 
with it, which is evidently very inferior to it in 
weight. ' This portion of fluid then flows out, 
becaufe it greatly exceeds in weight the column of 
air which is oppofed to it. But while it continues 
to fl w, nothing fuftains that which is above it, 
which flows neceflarily, while the preflure of the 
air at A furnilhes a new fupply of fluid to replace 
that which runs out. It is by thcfe means, that the 
water in the fiphon continues to flow without in- 
termiflion; becaufe the refiftance of the air in C is 
as much exceeded, as the length of the brarich B C 
of the fiphon exceeds that of the branch A B. In 
order to prove this, fuppofe there is added at C a 
tube to lengthen that branch, then it will plainly 
appear, that in a given time more water will flow 
than would have been difcharged without that 
augmentation to the branch B C. 

Since it is the preflTure of the air which elevates 
the fluid in the Ihort branch B A, it follows, that 
the height of this branch is limited to thirty-two 
feet when the fluid is water, becaufe the preflure of 
the atmofphere cannot elevate water higher; but 
when the liquor is mercury, the height of the Ihort 
branch ftiould not exceed thirty inches, becaufe the 
atmofphere cannot fuftain mercury at a greater 
height. ' ' 

III. The aftion of fluids on folid bodies immer- ' 

fed in them, has been already in part anticipated, 

in treating of fpecific gravity. It is neceflary, 

{ipwever, to refume that fubjeft to a certain extent 

Hb3- ' ia 

^o specific Gravity. [Book VI !• 

in this plaee, and I Ihall endeavour as much as pof-^ 
iible to avoid repetition. 

It is evident, that when a falid body is plungec| 
into a fluid, it occupies a fpace in .that fluid exactly 
equal to its own magnitude. The quantity of flui4 
then fo difplaced, either equals in denficy and confe- 
qucntly in weight, the folid which difplaced it ; or, 
on the contrary, one of die two muft weigh more 
than the other. In the laft cafe, which is moft com- 
mon, the quantity by which the heavier body fur- 
' pafles the lighter, is called the fpecific weight ox 

It has been obferved before, that fluids cxercifc 
{heir prcflure in all dirc^fHons, confequently a folid 
body plunged into a fluid is prefied at all points. 
It has alfo been proved, that this preflfurc increafcs 
in proportion to the height of the fluid j the prcf- 
fure, therefore, which the body undergoes, is great- 
er in proportion to the depth into whicli it is 
plunged. Laftly, it has been proved, that when twq 
^uids are placed in equipoife, their relpeftive 
iieights are in proportion to their denfitiesi and 
therefore bodies plunged tp ^n equal depth, arc 
coniprcfled according to the dcnfity of the refpcc- 
tive fluid. 

If a body is heavier than the fluid in which it is 
immerfed, it is evident that it will fmk to the bot- 
tom, by its fpecific gravity. If a body is lighter 
tiian the fame bulk of the fluid into which it is 
plunged, a part of it will fwim, and the reaiaining 
part which is immerfed difplaccs a quantity of 
X • ' ' fluid 

Cli^p. 2.] Swimming. 471 

fluid which weighs exa^y as much as tht whole of 
thcfoHd bcly"*^, 

^ « From what I have already explained, you mud necelTarily 
kave diicoYered the rationale of fink wg and fiwimming. You 
£lw that when a body was bulk for bu k heavier than the fiaid, 
by being immerfv-d it lofe^ only the weight of an equal bulk of 
the flujd, and confequently the refidual or remaining gravity of 
Ac folid mult carry it down to the bottom, or make \\,fink. 

On the other nand, if the folid has^ lefs weight in the fame 
bulk than the fiui^, ^henit cannot by its weight difplace or raife 
npwardf its whole bulk of the fluid, but only fo nyjch of it as is 
equal to its own weight, and from this deficiency in weight it 
wiP be only partly immerfed, and will' therefore fwim upon 
the upper part of the fluid. 

Of all the animals, however, thrown into the water, man is 
the moil helplefs; the brutecreation receive the art of fwimming 
from nature, while man can Qui/ acquire it by pradice ; the 
one efcaoes without danger, the other finks to the bottom* 
Seme have aflerted, that this arifes from the different fenfibilities 
rach have of the danger ) the brute, unterrified at his iicuation, 
^ruggles, w.iile his very fears fink -die lord of the creation. 

But much better reafons may be afiigned for thiii impotence of 
fnan in water, when compared to other animab ; and one is, 
that he has adlually more fpeciHc gravity, or contains more 
(Hatter within the fame furfacc than any other animal. The 
|runk of the body in other animals is large, ihd their extre- '' 
mities proportionably fmall ; in man it is the reverfe, his ex- 
tremities are vtr'^ large in proportion to his trunk. The fpe- 
^ific weight of the extremities is proportionably greater thai\ 
that of the trunk in all animals, and therefore man muH have 
;he grcateft weight in water, fince his extremities are the 

Befides this> other animals to fwim haire only to walk (as it 
were) forwards upon the water ; the motion they give their 
limbs in fwimming is exadly the fame they ufe upon land ; but 
it is different with man, who makes ufe of thofe limbs to help 
jbim forwards upon water, which he employ^to a "^txy differ- 
ent purpofe upon land.' Ad a m s's Le£iitrtSf Vol. iii. p. ^08. 

I?h4 • Id 

47^ theory of Swimming. [Book VII. 

If, for inftance, water is poured into « glafi 
vcflcl (fig. 5.) fumilbcd with a fmall cock near 
the bottom; if the height of the water in the vcflcl 
is marked with a fmall bandage of -thread or paper; 
andj laiUy, if a ball of wood is thrown into it, it will 
appear that part of the wood will be immcHcd, and 
part of it remain above the water, and that the 
immcrfed part will raife the water in the vcflcl juft 
as much as if a volume of water had been added 
equal to the folid contents of the part under water. 

If a quantity of water is then let out of the veflcl 
by means of the fmall cock, until the furface-is re- 
duced as low as the mark which pointed ou|: its 
height at the beginning of the proccft, it is clear, 
that the water drawn but in this manner will be 
equal in its folid contents to thofe of the immer&d 
part of the wooden ballj and alfo^ if this volume 
of water is weighed, it will be found to be of ex- 
adkly the fame weight as the whole ball of wood. 

Hence it follows, that Zr boat upon a river dis- 
places a quantity of water exaftly of the fame 
weight -with the boat and its lading; and if more 
weight is added, it will fink deeper in the water in 
the; fame proportion; and the immerfcd part is 
more or lefs in extent, according to the dehfity of 
the water. Hence, aa water when impregnated 
with fait, is heavier and denfer than pure water, as 
was formerly proved ♦$ it follows, that the 'feme 
boat and lading will draw lefs water (accordirt to 
^e feaman'sphrafe) in the ocean, than in a river of 

* Book vL chap. 7. 



Plate 6 

Fi<f. 1. 

Fuf. 2. 

G F. 

F^S 3- 

Fig. 4. 

f^ 3 



Chap- 2.] The Hydrometer. 47 j 

Ircfh water, and that IF it is laden ,to- the utmoft 
extent in fait water, it will fink when it comes into 
frelh water 

tjpon this principle depends the uft of the hy- 
drometer. For it will be foiind that bodies immer* 
fed in mercury, fuftain a greater lofs of weight, or 
require a greater power to fink them, than in fait 
water; in fait water than in frefh; and in pure wa- 
ter, they ftill fuftain a greater lofs of weight than in 
fpirits of wine, which is ^ lighter and lefs denle 

The hydrometer, then, is an inftrumcnt by which , 
the fpecific gravity of difiirent fluids is determined,^ 
The moft fimple, and that which is moft in ufe, con-- 
fifts of a glafs globe with a long narrow neck (plate 
VII. fig. I.) AQ divided all the' way up into 
equal parts. In ordpr that this inftrumcnt may fuftain 
kfelf in the middle of liquors in a vertical poficion, 
it is made in fuch a manner that the center of gra- 
vity is in the lower part of it; it is for this purpofc, 
that another fmall hollow ball S is placed under the 
larger ball, in which fome mercury is ufualljr 
lodged, but in fuch a quantity only as that the whole 
hydrometer fliall weigh about as much as an equal 
bulk of that fluid which is appointed tb be 

When the hydrometer is conftru6ted in this man- 
ner, if it is plunged in the liquors wliich are to 
.be compared, it will not entirely fink, becaufe it i^ 
fuppofed to be of a fpecific gravity, abput or nearly 
equal with that of the fluid. 


474 the Hydrometer. [Book VIL 

Ifi thcfeforc, the weight of the hydrometer is 
iuch, that it will fink in water as far as E, it wiE 
iink ilill deeper in lighter fluids; it will (ink for 
inflance in wine as far as F; in fpirits of wine as 
&r as G, &c. But if it is plunged into liquoii 
heavier than water, it will not fink fo far as E ; for 
example, in beer it will only fink to D, and always 
as ];nuch lefs as the liquor into which Jt is plunged is 
denfcr and confequentl^ heavier. 

By thi3 procefs it will be cafily difcovcred, whe- 
ther one kind of fluid is lighter than another with 
which it is compared ; but the proportion cannot 
be accurately determined; for in order to that, it 
would be neceflfary to know exactly the proporcioD 
between the tube AC and the balls B and S; 
which is impofnblc according to the above mode of 
conftnK^ting the inftcument ; and it would alio be 
further necef&ry that the tube A C Ihould be per- 
feftly cylindrical, ^which never is the cafe. The 
hioft certain mode of acquiring this exaA know- 
ledge is, to operate always with equal volumes of 
fluids : and for this purpofc, it is neceflary to make 
u e of Farenheit's hydrometer. 

This inflrument (fig. a.) is con^ofed of a fmall 
oval glafs bulb or botrie B ; the neck of which A 
C is very fmall, and terminates with a baibn D E> 
defigncd to receive fmall weights. 
_ The inftrumcnt is ballafled by means of a fmal| 
ball of glafs S fixed underheadi it, in which there is 
depofitcd fomc quickfilver. A fmall grain of 
fmalt {a) is fixed upon the neck^ an^ the inflni^ 
ment is then complete. * 


^h^p. a.] Fdfre^beif'S BydKometer. 475 

In order to make ufe of this hydri^ctcr, it is 

pcceflfary to begin by knowing its cjj^ft weight, 

Tvhich ihould be marked upon it, to prevent its 

being forgotten. The inftrmnent is tber; plunged 

into diftilled water; and by putting weights into the 

bafon D E, it is made to fink as far as the grain of 

fmalt {a). The weights wJiich were made ufe of to 

prcxluce this immerfion, added to the weight of 

the hydrometer, gives cxaftly the weight of the 

yolunae of ii^ater meafurcd by the inftrument. By 

repeating the fame operation upon any other fluid| 

the weight of the volume of that fluid mtafured by 

the hydrometer, may tc kpown with equal exadk- 

nefs. H^nce it follows, tha,r the quantity of thefe 

two volumes are equal, bfecaufe they are n>eafured 

by the fame inftrun^ent.: the difference of theif 

weight thpn wijl giye the- difference of thpir (pecific 

gravity^ or theijelation between ^heir den fities. To 

determine this relation ejfjiftly, the following pro- 

ppri;ioa rmift be obferved t The fpccific gravity of 

|he proved liqiipr, is to thart of diftilled .wajcra;5 the 

weight of a volume of that fluid meafured by the 

jiydromcter, is to tl^e weighjt of the volume of wa-r 

tcr alfo n>eafured by. it. If the fpecific gravity of 

V the one is known exaAly, tlje fpecific g^vity of the 

other may be determined by it, and alfo that of all 

other fluids which are praved in the fame m^a- 


The whole of what has been advanced in thii 

chapter, and in that of the firft book upon fpecific 

gravity, may be briefly fummed up in the following 

propofitioiis : Firft, when two bodies are equal in 

- their 

476 Recapitulatum of Principles [Book VII. 

their magnitude, bulk, or volume, their fpcciik 
gravities arc to each other as their denficies. So 
that one body has twice the fpecific gravity of 
another, when it has twice the denfity of that 
other body comprized in the fame (pace or magni- 
tude. , 

Secondly, when two bodies lofc an cqiial 
weight in the fame fluid, they have the lame mag- 
nitude or folid contents, whatever form they, may 
afTume, fincc they each lofc a weight equal to the 
bulk or volume of fluid which they difplace. 

Thirdly, the fpecific gravity of bodies is in- 
verfely as their bulk when their weights arc equaL 
As one body has twice the fpecific gravity of ano- 
ther, when with the fame weight, it has only half 
the magnitude of that other body* 

Fourthly, the fpecific gravities of two bodies arc 
in a dircft proportion to their denfides, an^ in an 
invcrfe proportion to their magnitudes. This 
propofition is a neceflkry confcqucnec of two pre- 
ceding, viz. of the firft and third. 

Fifthly, the fame body will lofc a greater quan- 
tity of its weight in a fluid fpecifically heavier than 
lA ^ lighter one; becaufe it will always lofe a por- 
tion of its weight equal to the weight of that bulk 
of fluid which it difplaces. It requires then a greater 
force to fuftain it in a lighter than in a heavier fluid: 
it will require more force to fuftain it in air than in 

Sixthly, the fpecific gravities of bodies of an 
equal weight (when weighed in a common balance) 
are proportionate to th^ weight which they lofe in 


Chap. ^.] . relative toffecific Gravity. 477 

the fame fluid. So that of two bodies of equal. 
^vcight3 if , the one lofes one- fifth and the otlier two- 
fifths of its weight in the fame fluid, the fpecific 
gravity of the firft is to that of the fecond as two 
to one. 

Seventhly, if a body is of the fame fpecific gra- 
vity as a fluid, when immcrfcd in that fluid it will 
be in equilibrium with it, and remain at any depth 
at which it is placed. 

Eiglithly, if a body fpecifically lighter than a fluid 
is plunged entirely into it, and then left to itfelf, it 
win remount with a force eqval to the excefs of 
weight which a volume of that flqid poffeflTes above 
an equal bulk of the body imifnerfed. 

Ninthly, the fpecific gravijfy of a folid is to that 
of a fluid heavier than itfelf, and upon which it will 
fwim, as the bulk of thc^immerfed' part is to the 
bulk of the whole body. So that if the magnitude 
or bulk of the immerfcd part is to the magnitude 
of the whole body as two to three, the fpecific gra- 
vity of the folid is to that of the fluid as two is to 

Tenthly, the weight and the magnitude of a 
body, and alfo the weight of a fluid fpecifica% 
heavier than the body, being given, Tuppofe it is 
required to find the force requifite to keep that body 
entirely immerfed in the fluid. As this force is 
equal to the fpecific weight of the fluid, find, by 
meatis of the given bulk of the folid, and the known 
weight of a cubic jfbot of the fluid, by the rule of 
three, the weight of a bulk of the fluid equal to the 
bulk of the folid. Subftraft from this weight, the 


478 RccnpituIaticH of Prin/^Us [Book VII: 

weight of the foUd, and the remainder wiH be the 
force required. For exanhp'e, fuppofe it was re- 
quited to find the force neceflary to retain andcr^ 
water a folid of eight ciibic feet in contents, and of 
four hundred pounds Weight, Since a cubic foof 
of water weighs aboUt feventy pounds, the w^Kght 
of eight cubic feet of water is five hundred and (ixty 
pounds; then iffour hundred pounds arc fubftraded, 
the one hundred and fixty remainder, is the force 
neceflary to keep the folid immerfed in ehc watjer^ 
and to prevent it from rifing to the furfacii. 

Eleventhly, the weight of a body fpecificaljf 
heavier than a flliid, and the weight bf that fluid 
fpe.cifically lighter, being given, fuppdfe it is re- 
quired to determine the cavity which diat body 
Ihould have, in order that it may fwim upon thrf 

The weight of ^ cubic foot of the fluid being 
given, the bulk of the portion of the fluid equal in 
weight to that of the body, is found by the rule of* 
three. If then the cavity of the body is made foi 
that the bulk may be a little larger than tJie magni- 
tude already found, the body will have leis weight 
Under the fame magnitude than the fluids For ex- 
afnple, fuppofe that it is required to make a ball ' 
of iron of thirty pounds, and of fuch a magnitude 
as mat it will fwim upon water. Since the weight 
of a cubic foot of water is feventy pounds, a vo- 
Itime of v/ater weighing thirty pounds v/ill be three- 
fcvenths of a cubic foot : hende it will be eafy to 
find what the diameter of a fpherc mufl: be, the (olid 
contents of which fliall be three-fevenths of a cubic 


Chap, a.] relative to fpecific Gravity. 479 

foot. Therefore, the ball of iron muft be made 
hollow within, and in fuch a manner that its diame- 
ter may be greater than die diameter of a Iphere,. 
the fblid contents of which is three- fev.enths of a cu- 
bic foot: if this ball is made eleven inches three 
lines in diameter, it will fwim. * Hence we fee 
that it is not neceflary for a body to fwim, that ic 
ihould be compofed of matter ipccifically lighter 
than water; it fuffices that its bulk or volume 
fhould be great and its gravity fmall: for though 
copper is about eight times as heavy as water, yet 
military men have occafionally employed boats of 
copper in conftrufting bridges for the paffage of 

A copious tabid of (pecific gravities is given in the 
appendix to this volume. 


£ 4^o 3 BookVn, 

Chap. IlL 


X}fth€ Di/chargeofFMs thrOugh/malUfertMres.-^^ Hfjch^fff 
ff fluids tbreugb JucceJJvve Pifes.^-^Artificiai F^aaimwa^ 
Fumps.^Tbe Raifin^ Fmi^.^^The Forcing Pump. — ThSMckag 
Fymp.—Tbe Compound Pump.— The Fire Engim^^Mmm if 
Water in Conduit Pipes. '^0/ciHatOfy Moii^m rf Water n < 

. tiphon.^^Ofcillatory Motion of Waves. ^^Mot ton of fFietk 
0iQed upon hj Water ; and ConftruBion of Water Milh. 

THE fciencc which has for its obje£t thcmoooD 
of fluids is called hydraulics ; and its imme- 
diate application is to furnifti us with the means of 
conducting water from one fituation to another, by 
canals or aqueduds, and to elevate it by puraps^ 
jets-deaux, and other hydraulic engines, either for 
the purpofes of ornament or ufe. 

In treating of this fubje6t I (hall commence wd 
the fimpleft principles, and fhall firft Ipeak of the 
difcharge of fluids through fmall apertures. 

When water flows from a veflel which has a hole 
or aperture in the bottom, fmall in comparifon lo 
the width of the vcflfel, the water defcends vertical)/, 
and the furface appears fmooth, but at three or 
four inches from the bottom the particles turnfiom 

• Almoft the whole of this chapter, and great part of tlw 
preceding, are tranflated from the firft volume of BriUbo'i 
*« Traitc Elcmcntairc dc PhyCquc/' Chap, VIII. 


Chap. 3.3 Flow of Water through fitdU Apertures. 48 r 

rthis dir^dion, and proceed on all fid^s with a motioil 
more or Icfs oblique towards the aperture. The 
fame efFcdt takes place when water flows through 
an aperture laterally. The tendency of the par- 
ticles towards the apertyre is a neceflary confe-^ 
quencc of their perfc£t mobility j for they will cer- 
tainly be direded towards the p<Mnt where there 
is the lead: refiftance^ and that point is the aper* 

It is alfo to. be obferved, that in this cafe^ at t 
Imall diftance from the bottom^ a kind of funnel is 
fortned in the water> the point of which correiponds 
to the center of the aperture 1 when> however, the 
water flows through a lateral orifice or aperture^ 
there is formed only a kind of half funnel^ which 
does not appear to commence till the furface is near 
touching the upper fide of the hole. It is probable 
that the funnel begins to form . itfelf from the firft 
moment of the flow ; but it doe3 not become per- 
ceptible till the furface is only at a fmall difl:ancG 
from the. bottom. 

It appears alfo, that the funnel commences highnr 
or lower, according to the width of the bottom; 
and that the formation of it is lefs prompt or lefs 
perceptible, according to the proportion of the 
aperture to the extent of the bottom. The funnel 
is alfo augmented by any roughnels . w^ich may 
cxift at the fides or bottom of the ve0eL 

Water flows out of a fmall hole in the bottom ofa 
vcfiel with a velocity equal to that whicha ponderous 

Vol. II. I i body 

4Sa JXjafarp^FUds [BookVli 

body acquires iii jfallkig from a height eqiial to the 
veitical height of the furfkct of the fluid above the 

The fame law takes j^ace in a latend orifice; 
for the prefllire of the fluid is equal (ac die tuat 
depth) in all direftions, and confeqxiently- produces 
the feme degree of velocity. 
~ A fluids in rumiing 6vk of an aperture, acquires! 
velocity fufficient to make it remount to a vertical 
height equal to that of thefur&ceof the fluid abbye 
the aperturey in> the iame mamier as a falling body 
acquires a velocity capable of making it aicead fi) 
the height from which it defcended* 
. It is evident, from the theory of falling bodies, 
that if the velocity of the fluid in running duioi^ 
the aperture was tiniformly continued, the fluid 
woidd move through a fpace double, the hergitof 
the fluid above the aperture in the fame time that i 
failing body would employ in defcending from that 
height. '^ 

The height being the fame, the velocity of the 
flaid in running out of the orifice will alwaj^b^ 
the fame, whatever the fpecies of the fluid may b^ 
and whatever its denfity. -It is. trucj'^that when the 
fluid has more denfity it prclfes^ more forcibly, but 
then the mafs i$ more confiderable, and it is evi* 
dene, that when the moving pawcrs-are proporrioo^ 
to the malTesAvWdi'they put iA motion, the vclo* 
cities ace equadw > . 
< .The quantities df a flind dif<^^ged in the fame 


Chap. 3.3 through ^finall Apertures. 483 

Ipace of time dirough difiei-ent orifices, fuppofing 
the veflels equally fiill during the whole of (he ex- 
periment, are to each other as the produ<Sl3 of the 
area$ of the apertures by the fquare root$. of die 
lieights. For inftance^ it has been proved by expe- 
riment, that a circular orifice of an inch diameter, 
made in a thin vefTel or partition, and undef a fur- 
face of fluid four feet in height, will furnifh, in one 
minute of time, five thoufand four -hundred and 
thirty-fix cubic inches French. 

If, therefore, it was an objeft to afcertain how 
much a circular orifice of two inches diameter, 
undef nine feet of height fi*om the furiace of the 
water, would furnilh in the fame time, the fol- 
lowing proportion muft be employed (it miift be 
obferved, that the orifice of two inches is four times 
as great as an orifice of one inch, becaufe the areas 
of circles are as the fquares of their diameters) : 

I X a/ 4 • 4 X v/ 9 r: S^2^ • ^ 
Or at length 

2 : 12 :: 5436 : 32616 


Therefore 3.26 1 6 cubic bches of water 
will flow from an aperture of two inches in dianie- 
ter in one minute, the orifice being mkde nme 
inches from the furface, which is fuppofed to be 
kept at that height the whole time, 

H 2 If 

4^4 Difcbarge rf Hmis [BookVIL 

If a vcflcl of a prifmatk form is Riled with wa- 
ter, and permitted to empty itfelf entirely through 
an (HiBce at the bottom, and the time that it con- 
fumes in emptying itfeif is observed ; and if after- 
wards, having rcplenifhed the veflel^ the water is 
made to flow through the fame aperture, the vcflcl 
bdng kept foil the whole time, there will run out 
in thik fecondinftance, during the fame time that the 
veflel took to empty itfelf at firft, a quantity of 
water double that which runs out in the fi/ft cafe, 
lor the abftradtion of the water produces a kind of 
funnel, which in this laft cafe does not take pkcc. 

We often perceive water flow through lateral 
apertures, which, though fmall in compariibn to ^ 
width of the rcfcrvoirs, cannot be regarded as hav- 
ing all their points at an equd diftance from die 
fur&ce of the fluid ; fuch, for example, as At 
apertures through which water ibmetimes flows in 
mills. The common method o( determining the j 
quantity difchaiged is as follows : fuppole, in the 
firft place, the aperture to be flopped up by a plate 
of metal, which is perforated with a number d 
holes; if each of thefe holes is regarded as 
particular and infulatcd, the rapidity of the flow 
through each will be according to the correfpondeot 
height of the fluid ; then if the number of hob 
are multiplied ad infinitum^ or, which will amount 
to the fame thing, if the plate is fuppofed to beco- 
tifcly taken away, the velocity at each point of fA^ 
fuppofed orifice will be according to the corrc' 
ipondcnt height of the fluid; and in cftimatingtfc 


Chap. >] through Jma^ Jperturef. 485 

quancicy of water diicbargedj ibme attention muft 
be paid to the inequality of the motion; yet it 
muft not be aflerted that this reafoning is entirely 
conclufive. In proportion as the fum of the fmall 
holes made in the plate is fmall in comparifon 
with the fize of the rcfervoir, the portions of water 
which flow through each hole are forced out by the 
abfolute weight of the column above; but the 
moment that the number of apertures augment 
ad infinitum^ and the ft reams of water >vhich 
run through them become contiguous^ it cannot 
be clearly faid that the liquid flows in the fanne 
manner as through fmall infulated holes; yet as 
this hypothefis gives a refult fufficiendy conform- 
able to experiments, it may be ufcfiil to prefcrve 
itj and the more fo> as it leads to very iimple calcu- 
lations, and in all common queftions this fimplicity 
may be preferable to the minutenefs of fr^dtional 

The quantity of water which ifliues from thefe 
apertures in a given time is not fo great as their 
fize might at flrft fuggeft, becaufe the ftream is 
contracted by running out of each oriBce^ and that 
contraAion extends to a diftance nearly equal to 
half the diameter of the aperture ; and the diame- 
ter of the contracted ftream is to the diameter of the 
aperture a little more than as three to four, or as three 
and one-fixth to four, or nineteen to twenty-four ; 
fo that its area is to that of the aperture as ten to 
fixtcen. It is nearly the fame when water flows 
through lateral apertures. The contradtion of the 
I i 3 ftream 

48« Bijcbarge of Fluids [Book VII. 

ftream is a proof of what has been before ftaiedi 
viz. chat withinfide a veflelj the lateral parddo 
direft chemleives towards the orifice with a motion 
more or lefs oblique -, and this oblique motion may 
be decompofed into two forces^ the one parallel m 
the plane of the orifice, and which contrads the 
ftream ; the other perpendicular to the (ame plane, 
and the only one which produces the efflux. 

This contraftion occurs alfo when water is made 
to flow through pipes, and that at the entrance of 
the water into the pipe, and not at its exit, where Ac 
ftream prcfcrves a cylindrical form. I fliall prove 
that this contraction diminiOies, in a lenfible man- 
ner, the quantity of water which would naturally 

In order to afcertam thefe fads by experiment, 
many have been made. In all the following in- 
ftances the orifices, through which the water flow- 
ed, were pierced perpendicularly through plates of 
copper of about onc-twenty-fburth of an inch 
thick, and the time of each experiment is reduced 
to one minute. 


Chap. 3.] tbrougb/mdi j^gtiures. 487. 

The conftant height of the water abdvc ^^^^S^ 
the center of each orifice wis 1 1 feet fiiraiflil 

8 inches 10 lines. *^. '" * ' 


Exp'. I. Through an horizontal cir- 
cular orifice of 4 inch (6 
lines) diameter - - 2,3 1 1 

a. Through ditto of i. inch 

diameter - - - 9^28 1 

3. Through ditto cf i inches 
diameter - - - 37*203. 

4. Through an horizontal reA^ 
angular orifice of i inch 

long and ^ inch wide - ^^933 

5. Through an horizontal (quare 

orifice of I inch the fide - 1 1,8 17 

6. Through ditto of 2 inches 

each fide of the orifice - 47*361 

Conftant height z= 9 feet. 

7. Through a lateral circular 

orifice of ^ inch diameter - a,o i S 

8. Through ditto of i inch 
diameter • - - 8,135 

Conftant height zr 4 feet. 

9. Through a lateral circular 

orifice of 4 inch diameter - i*3 J3 

10. Through ditto, of i inch 
diameter - - - 5*436 

Conftant height :=: xV I'^ch. 

11. Through a lateral circular 

orifice of i inch diameter - 628 

I i 4 It 

48S Di/cbargetf Fluids £Book VII 

It follows from the preceding table^ 

1. That thequaotides of water dilcharged in the 
fame time, by diiFerent apertures, under the &mc 
height of furface in the refcrvoir, arc to each odicr 
nearly as the areas of the apertures. Compare 
together the refults of the fecond and third experi- 
ments, of which the areas of the orifices are in the 
proportion of one to four, and it will be found 
that the quantities of water afforded, viz. nine 
thoufand two hundred and eighty-one cubic inches, 

' and thirty-feven thoufand two hundred and three 
inches, arc very nearly in the faoK proportion. 

2. That the quantities of water difcharged in the 
fame time through the fame aperture, under diSi:- 
rent heights of furface in the refervoirs, arc to each 
other nearly as the fquare roots of the correfpond- 
ing heights of the water in the refervoir above the 
center of the aperture. Compare together the re- 
fults of the eighth and fenth experiments, w^jcre 
the heighths of the refervoir? are nine and four feet, 
the fquare roots of which are three and two, and it 
will be found that the two qyantides of water, eight 

, thouftnd one hundred and thirty-five cubic inches, 
and five thoufand four hundred and thirty-fix cublf 
inches, which run through t;he fame orifice of one 
inch diameter under the different heights of nine 
feet and four feet, are to each other nearly in the 
proportion of three to two. 

3. That in general the quantities of water dif- 
charged in the fame time through different aper- 
tures, under different heights of furface in the re- 
fervoirs, are to each odicr as the areas of the aper- 


Chap. 3,] ^hrou^JmaU AftftjirBs. 4*9. 

•cures are to the fquare roots of the heights df water 
in chcrelervoirs. 

4. That in confequence of the friftion, thefmaU 
apertures fumifli a Icfs quantity of water in propor- 
tion than the great ones, under the fan^e height of 
water in the refervoirj' becaufe, comparatively ta 
the extent of the area of each orifice, there are more 
points of fri£^ion againd the fides^of the orifice in, 
the fmall than there are in the great ones % for the 
tiircuixiferences do not diminiih fo much as the 

5. That of rilany apertures of equal areas, thtt 
of which the circumference is the leaft will, on ac- 
count of the friftion, furnifli more water than the, 
others, under the fame height of the refcrydr^ 
circular apemires are, for this reafon, the mod ad- 
vantageous of all; for the circumference of a circle 
is the fhortefl. line that can be made ufe of to inclofc 
a given fpac?j therefore there is lefs furface of 
fridUon relatively to the fize of the area. 

It is eafy to perceive, that the quantity of water 
difcharged in the table of experiments is not near 
fo great as might be expeftcd from the extent of the 
areas and the heights of the refcrvoirs. The quan- 
tity is in faft diminifhed by the friftion, and ftill 
more by the contraction of the ftream ; for the velo- 
city which is in proportion to the entire altitude of 
the flijid is not fenfibly changed. Suppofing, firft, that 
rbc area of the ftream is the fame as that of the ori- 
fice; and fuppofing, fecondly, that the ftream is 
concraftcd, then the difference of the quantititrs 
afibrded is as .fixteen to ten; that is, /uppofing 


4^0 Di/cbarge of Fluids [Book VIL 

Ac area of the aperture to be dtminifiied in the pro- 
portion of (ixteen to ten> the difcharge of the fiiud 
out of veflek kept equally full may be determined 
with fufficient exaftnefs. By the expreflioQ, 
an inch <^ watery is undcrftood the quantity wbidi 
flows out of a circular and lateral orifice of oneiod 
dianieter, the furface of the water being conftanti? 
kept fevcn -twelfths of an inch above the center of 
the orifice. This is the cafe wkh the eleventh ex- 
periment in the preceding table^ where it appean 
that the quantity of water furniflied is fix hui^Jrcd 
and twenty-eight cubic inches. M. Mariotte, who 
made the fame experiment, found the quantity to 
be a little more; but it is probable that he might 
commit a fmall error, becaufe the experiment I 
have juft cited was made, M. Briflfon informs us, 
with the utmoft care and attention- A (French) 
pint of water, he adds^ inftcad of weighing two 
pounds, as is commonly believed, is proved to fell 
Ihort of that weight confiderably, as will be ce- 
dent by ftriftly examining that experiment. 

Thefe fafts being prcmifcd, I fhall requcft the 
attention of the reader, fecondly, to the diicbargc of 
fluids through additional pipes. 

When, inftead of caufing water to pafs through an 
aperture made in a thin fubftance, it is made to 
flow through an additional vertical pipe of the fame 
diameter with the orifice, the quantity of water 
difcharged is more confiderable, becaufe the con- 
traftion of the ftream is greater in the firft cafe 
than in the fecond. 


Chap- 3.]' ; Ihrwgh aMtimalPipeu 491 

In the following experiments, the conftant height 
of the water in the relervoir above the^ upper bafe 
of the additional vertical pipe is 11 feet 8-^^ inches 
(French) and the diameter of the pipe one inch. 

The variable heights of the 
tube cxprefled in jipes. 

Exper. I. - - 48 f The water 
1 running 
^- - - ^4<througka 

!Thc water 
not filling 
the pipe. 

Numl)er of cubic inched 
of wster difeltarjediii 
one minute. 

- 12,274 

- 12,188 

- 12,168 

- 9^282 

It appears from this cable of experiments, that the 
longer the vertical pipe is, the greater will be the 
quantity of water difcharged, becaufe the contrac- , 
tion of the ftream is lefs, as may be feen by com- 
paring the three firft experiments. There is al- 
ways, however, fome contraftion, though the water 
appears to flow out of a full pipe. 

In comparing the quantities of water difcharged 
in the third and fourth experiments, it will appear, 
that the two quantities, 12,168 cubic inches and 
9,282 cubic indies, are to each other nearly in the 
relation of thirteen to ten ; but it has been obfcrved 
before, that the quantity of water difcharged 
througlj an aperture made in a thin fubflance, if the 
ftream was not contrafted, woyld be to the quan- 
I tity 

49^ Difcbargi of Fluids tbrcugb [Book VIL 

my of water difchaiged throogh the fame orifice, 
if the ftream was contracted, nearly as fixteeo to tcik 
Hence then it may be concluded^ diat the height of 
the water in the refervoir and the different aper- 
tures being the fame> the quantity of water difcharg- 
ed through an orifice made in a thin fuUtancc, ta 
which there was no contraction of the- (bream, the 
quantity of water diicharged ^through an additional 
pipe, and the quantity which would flow chrougH an 
orifice made in a thin partition, in which there was a 
contraction of the ftream, are to each other neatly 
as the three nambers> fixteen, thirteen, ten^ and 
thefe proportions are found fufficiendy accurate fer 
common purpofes. 

Hence alfo it may be inferred, that additional 
pipes counteract only in part the contraction of the 
ftream. TKe nioft fenfible of all contradions of 
this nature is that which takes place when water 
flows from a large referVoir through a finaU aperture 
made in a thin fubftance. 

If the additional pipe, inftead of being vertical, or 
placed in the bottom of the veflel or refervoir, is 
horizontal, or placed in the fide, it will afibrd the 
fame quantity of water, provided that it is of the 
iame length, and that the exterior aperture is placed 
at the fame diftance below the furfkce of the water 
in the refervoir. 

If the additional pipe, inftead of being cylindrical, 
is conical, having its largeft bafe attached to the fide 
of the refervoir, it will produce a much greater quan- 
tity of water. The moft advantageous ferm, in- 
deed, for procuring the greateft quantity of water 


.Chap.* 3-1 iMiiiond Pipes. 49^ 

in a giv^cn time through a certain aperture, is that 
which the ftrcam itfclf naturally aflumes m coming 
out of an aperture in a thin fubftance ; that is, «the 
form given to the pipe (hould be that of a truncated 
cone, the diameter of the fmaller bafc of which 
ihould be the fame as that of the aperture through 
which the water is to flow. 

It is neceflkry alfo» that the area of the Imaller 
bafe ihould be to the area of the greater as ten 
to fixteen; and the diftance between the two bafes' 
fliould be nearly equal to half the diameter of the 
greater bafe. The remainder of the length of the 
pipe may be either cylindrical or prifmadc. The 
diicharge will then be equally abundant with that 
which would take place through an aperture equal 
to the finaller bafe made in a thin partition, and 
in which the itream fufFered no contraAion. This 
form may be applied to practice whenever it is ref- 
quired to draw a certain quantity of water from a 
river by an aqueduft, &c. through a canal or late- 
jal pipe. 

If we compare the difierent quantities of water 
' difcharged through additional pipes of different di- 
ameters with different altitudes of the water in the 
reftrvoirs, we (hall . have the reftilts ftated in the 
following table, the addidonal pipes being fup« 
pofcd to be two inches long, and vertical, or placed 
indie bottom of the refervoir. 


45* ^ Difcharge of Fluids through [BookVIl 

The confbnt h«ight 
of the water above 
the aperture. 

Ex* i.l 




■^ j .1h»«8. j 



The dia^iefcr of Ae addi- 
tional pipe? in twelfths of 
an inch (lines). 

6 t . The water rttnning 
S through afnH pipe. 

7 The wat^r' not fbl- 
j: lowing dte fides. . 





? The water not filling 
3 the tube* 

The.watec. ranning 
through a full pipe* 

No. of cubic 
inches dis- 
charged in 



The firft inferencjC from ihcfe experiments is> 
ihat the quaftjtity of water dJfcharged by diflfercnt 
additional pipes, under the i^mt height of water in 
the refervoir, i& proportional to the areas of the 
apertures, or to the fquares of their diameters. 

Secondly, if appears that the quantities of water 
difcharged through additional pipes of the fame 
diameter, under diflFcrent altitudes of water in the 
refervoir, are proportional to the fqtiard root of the 

Thirdly, that in general the quantities of watcf 
difcharged in the. fame fpace.of time through dif- 
ferent additional pipes, under diflferent heights of 
water in the refervoir, are to each other nearly as 
the produft of the fquare of the diameters of the 
pipes by the fquare root of the altitude of the 
refer voirs. 


Chap/j.] ' oMtimalPipts. ' 49 j 

The efflux of water, therefore, through addi- 
tional pipes, follows the fame laws as water when 
difcharg^ through apertures made in thin fub- 
ilances. On. thefe ei^eriments the following table 
was formed^ • of the quailitides of water difcharged 
through a given aperture made in a thin fubftance, 
fuppoQng the ftneam to fufFer no contraftion, or 
through the fame aperture with a contraftion of the 
ftream^ or through the fame aperture with an 
addidonal pipe* 

height of 
the vt^ter 
in the re- 
above the 




- 2 





8 ^ 




Cabic inches of 
water difcharg- 
ed in one mi- 
nute through an 
ap.erture of one 
inch diameter 
without any 
contradibn of 
the Aream. 









Cubic inches of 
water difcharg- 
ed in one mi- 
nute through an 
additional pipe 
of one inch dia- 
meter and two 
inches long. 

Cubic inches 
of water dif- 
charged in one 
minute through 
an aperture of 
one inch dia- 
meter with a 








. 5436 











1 1151 

. 8574 











III. There 

4^ Jirtifiid Fountains. [Book Vlt^ 

IIL There is no applicaciott of the dodrines of 
fiydrauHcs more furprifing, or more gratifying to 
Ae eye, than that which is feen in the variety of 
artificial fountains, or jets d'cau, which the inge- 
nuity of man has been able to conftrud for orna- 
ment in general* and for ufe in fomc inftances, par- 
titriilarly in warm climates. The principles on 
Vhich thefc are conflrufted it will not be difBcul^ 
fcftcr what has been dated, fully to comprehend. 

Whatever may be the diredion of the jet or 
fountain, the quantity of water expended will be 
the fame, provided that the adjutagp *, and the 
fieight of the rcfervoir above the adjutage, is the 
£nie. This is a neccfTary confequence of the 
equal preiTure of Buids in all dircAions^ 

Water, when difchargcd through an ajutage, 
hoNvevcr fmall it may be, has a velocity fuificient 
to raife it to the height of the furface of the water 
contained in the rcfervoir; fo that a vertical jet d' 
ran throws Up the water as high as the rcfervoir 
whence it proceeds, if nothing obflruds it. 

There are, however, many caufes which con- 
tribute to dirainifh the elevation of water by jers 
d'eau. Firfl, the friction in the pipes from the rcfer- 
voir to the ajutage ; fecondly, the fridion againft 
the circumference of the aperture^ thirdly, the 
refiftance of the air to the motion of the column ^ 
fourthly, the gravity of the particles of water 
themiclves, which, in rifing, lofe fome of their velo- 
city> and recoil upon thofe which fuccced them. 

* A tube which is fitted to the mouth of the vcfTel througii 
which the founuin is plajred. 


C hap. 3.] cr Jgu d *Eau. 497 

Thus, by inclining the pipe a little, we find that 
the water will rife higher than when it is exaftjy 
vertical i but in this cafe, the efFeft is not fo agree- 
able to the eye of the fpeftator, as when the water 
whicli rifes above the pipe into the air falls perpen- 
dicularly,, in a nr.anner, back upon itfelf. 

When the ajutage is placed in an oblique direc- 
tion to the horizon, the fierce of the projeftion and 
the gravity of the water caufe the liream which af- 
ctnds into the air to forni a parabola, the amplitude 
of which is in proportion to the height of the refer- 

When the ajutage is placed horizontally, tht 
water forms a femi parabola. 

Fountains elevate the v\ ater in proportion as the 
apeiture of their ajutages is large 3 becaufc, firft, if 
two jets d'eaux proceeding from the fame refcrvoir, 
and flowing from their ajutages with an equal degree 
of velocity, the greater will, in the (irlt place, expe- 
rience Icfs friftion ; and fecondly, it has a greater 
mafs, and confequently more power to overcome 
the obftacles which may oppofc it. 

But, though large jrts d'cau elevate water 
higher than f rialU onet, tlicy do not expend a 
greater qujintity in proportion; fur the quantity of 
water difcharged is avthe produft of the aperture 
of the ajucag;; by the degree of velocity at the time 
cfthe dilchargej and thft velocity is the fame in 
both, no allowance being made for the friction. 

In order to make large fountains elevate water 
higher than fmall ones, it is evidently neceflfary that 
the conducing pipes Ihould be fufficiently large to 
furnijh water in abundance ; for if they are fmall, 
• Vol. IL K k experience 

498 Artificial ^Book Vll, 

experience proves that the fmall fountains in that 
cafe will elevate water higher than larger ones ; it 
follows then, that the diameter of die pipe, which 
conveys the water, (hould be in proportion to that 
of the ajutage, in order to elevate the water to the 
greateft poflible height. 

If we compare two different jets d' cau, and arc 
defirous that each (hould elevate water to the greateft 
poflible height, it is ncccffary that the iquares of the 
diameters of the conduit pipes fhould be in propor- 
tion to each other in the compound ratio of the dia- 
' meters of the ajutages and the fquare root of the 
altitudes of the refervoirs. Thus, if It is known bj- 
I experiment what the diameter of a conduit pipe 

fliould be, to fupply an ajutage of given dimcn- 
fions, it may be eafily determined what the diame- 
I tcr of another pipe fhould be to furnifh another 

' ajutage of a determinate fize, the height of the rc- 

I fervoir being alfo given. , 

I It has been proved by experiments, that when the 

j diameter of the ajutage is half an inch, and the 

height of the refcrvoir fifty-two feet, thcdiametcr dL 
the pipe which condufts the water ought to be 
three inches and a quarter; and that for an ajutage 
of half an inch diameter, the height of the refcrvoir 
being fixteen feet, the diameter of the pipe ought to 
be about two inches and one-third. There is no 
inconvenience in making the conduit pipe of a great- 
er diameter than is required by this rule; but on the 
contrary, there would be an inconvenience ia 
making it of a fmaller diameter. 

Sometimes the ajutage is made in the form of t 
xone, and fometiraes in that of a cylinder j but 


fcKap*3*!l Pountainu 495 

thofe who conceive that it is indifferent in which 
ofthofe forms it is made are miftaken, for the cylin- 
drical fdrmib by far the moft difad^antageous. 

By comparing many experiments made upon 
artificial fountains, it has been determined, that the 
differences between the altitudes of vertical jtts and 
the height of their refervoirs are to each other as 
the fquares of the altitudes of the former. If 
then it is known what quantity of water a jet ele- 
vates at a certain height of the refervoir, the quan- 
tity which tiny other jet of a given height will 
elevate, compared with the height of its refervoir, 
may te eafily found by the rule of fingle proportion. 

When it is neceffary to bend the concjufting 
pipes, the utmofi: care fhould be taken to avoid 
bending them' at right angles, for the ftriking of 
the current againft thefe angles very confiderably 
dimi'nirties the velocity. 

The following table will greatly facilitate the 
application of thefe principles. 

The heights of jets, and the correfpondent 
heights of refervoirs, are found in the two firfl: 
cohimns. The third column contains in (Paris) 
pints, of which thirty-fix make a cubic foot, the 
quantities of water difcharged in one minute 
through an ajutage of half an inch diameter, rela- 
tively to the heights in the fecond column. The 
quantity difcharged through art ajutage of h^lf an 
inch xiiameter being known, the quantity^ which 
will be difcharged by any other ajutage, urSer the 
fame height of the refervoir, may be found by fingle 
proportion ; for it has already been proved, that the 
quantities of water difcharged are to each other as 
K k 2 Ihe 

500 Artificial Fountains. [Book VlL 

the areas of the ajutages, or as the iquarcs of their 
diameters. In the fourth column arc found the 
diameters for the condufting pipes of an ajutage of 
half an inch diameter, according to the heights in 
the fecond column. The diameters of pipes for 
other ajutages, and other heights of the rcfervoir, 
arc found by following the preceding rule. 

Fra£ttons are not obfervcd in the calculations for 
the two laft columns. 


O-untitics of w»- 

wt iJifclui^eJ in 

Diameters of the 

The Iieights 

The heigliK of 

«,ue niiimte 

pipes accanb-i 

ut jcif, «x- 

leicrvoin., in feet 

thiotigh an <ju. 

to the zt< aoi] jJ 

pretlej in 

and iii'.iics. 

tase of nJf an 

eulumns, in 


inch Ji.imeter, in 



Feet. Inches. 




S J 




JO 4 




>5 9 




21 4 




27 I 








39 » 




45 4 




51. 9 




58 4 




65 i 








79 I 




86 4 




93 9 




. »OI 4 




109 1 








125 I 



100 J 

^33 4 


» 4? 

IV. From 

Chap. 3.3 ' Pumps^ 501 

IV. From objefts of mere plealunc and orna- 
ment, our attention is next folicited to an invention 
of eminent utility, and of ancient date, though* the 
modern improvements arc very confidcrablc even 
in this branch of' mechanics. 

Pumps are hydraulic engines, defigned for the 
purpofe of elevating water j they are compofed of 
hollow cylinders AB (Plate VII. Fig. 3.) orEK 
(Plate VIII .fig. I.) of an equal diameter throughout: 
their whole length, which is called the body of the pump ^ 
and in which a kind of ilopple I, called the pi^ofty is 
made to Aide, or move up and down. The pifton 
is put in motion by means of a rod of metal X x, 
at the extremity of which X the handle is placed^ 
and elevated by , the lever X Y, or by fomc other 
contrivance 5 to this is annexed a pipe A T (Plate 
VII. Fig. 3.) to conduift the water to the height 
required 5 and, laftly, the fuckers S s. 

There are feveral kinds of pumps •; fomc ?rc 
, called fucking pumps and others forcing pumps, 
and there are others which arc at thfe fame time 
both fucking and forcing pumps. 

The rai/mg pump is compofed of the body of the 
pump A B, (Plate VII. Fig. 3.) to the lower pare 
of which is affixed the end of a pipe B N, open at 
the bottom, or (which is ftill better) pierced with 
holes its whole length, in fuch a manner that large 
pieces of dirt and rubbilh may be prevented from 
entering the body of the pump. At the union of 
this enu of the pipe with the body of the pump is 
pUced a valve or fucker /, which, when raifed up 
^y the preffurc of the water beneath, permits the 
Kk3 fluid 

5oa fhe raifing [Book VII, 

fluid to afcend into the body of the pump, but which, 
by being preflcd down again by^ the aflion of the 
pump, prevents effcaually the efflux of the water by 
the fame aperture. In the bo Jy of the punnp there is 
a box or piflon I, pierced quite through, furnifiied 
at the^ upper end with a fucker S^ and joined at;rj 
by the alTiftance of a bead fomewhat in the form of 
chat of a pair of compaffes, to the rod jirX, wjiicft 
enables it to aft by the aid of a lever X Z Y. At 
the upper part A of the* body of the pun^ ii 
plated the raifing pipe A T, which has its fpowll 
T This pump ought to be placed in a well « 
bafon, in fuch a manner that the body of ite> 
pump AB fhouid be entirely under the furfacedf 
the water A A. 

Now if the pifton I is raifed by lowering fkc" 
extremity Y of the lever Y Z X, fo that the kfir: 
may aflbme the pofition j^Z », the pidon will riie% 
the body of the pump, where it will create an ti»^ 
perfeft vacuum equal to the diftance X^», aUff 
confcquently the water beneath will raifc the fudaK 
Sy and will pafs cut of the bafbn into the pudqir 
When the pifton is lowered again, this preffiot 
caufes the fucker s to clofc, and the fucker S to l^ 
up ; hence the water which was below the piftfit 
is then above it. By a fecond exeption of At 
pifton, this quantity of water is elevated, aodby ibl 
fame mcchanifm a frelh quantity is |>ermittcd 19 
pafs into the pump, and afterwards to rMc above Ac 
pifton, in the fame manner, as the firft portion nil 
raifed j fo that by a cert?dn number of exertiont^if 
the pifton, the raifino; pipe AT is filled. Whea 


31. ps^z 


Chap. 3.] Pump. 350 

this is accompliflied , at every exertion or ftrokc of the 
pifton there is cjefted at the fpout or difcharging 
pipe T a mafs of water equal to a cylinder, the bafc 
of which is equal to the width of the pifton, and of 
a height equal to the fpace through which the pifton 
pafles in the body of the pump. This fp^ce is 
commonly called the play of the pifton. 

It is not difficult to cftimate the weight of the 
column of water with which the pifton is charged, 
when the railing pipe is full, and confequently the 
force which is neceflary to be exerted in Y in order 
to work the pump. It has been obferved before, 
that fluids prefs in proportion to their perpendicular 
height, and the width of the bafe which oppofes 
their defcent. In a pump, this bafc is the pifton, 
and the perpendicular height is that of the raifing 
pipe above the furface of the water; fo that when 
the raifing pipe is full, the charge upon the pifton 
is equal to the weight of a cylinder of water, the 
diameter of which is equal to that of the pifton, and 
the height equal to that of the raifing pipe above die 
furface of the water, whatever may be the diameter 
of the mounting pipe j and this charge or weight 
upon the pifton is eafily calculated, when it is known 
that a cylinder of water of one foot diameter and one 
foot high weighs about fifty-five (French) pounds. 

It follows, therefore, that the weight of a column 
of water is not diminiftied by diminifhing the dia- 
meter of the raifing pipe; but that, on the contrary^ 
the refiftance which ought to be overcome is even 
augmented on account of the increafe of the frig- 
pOH; whicfi is more confiderable in fmall pipes 
K k 4 than 

504 deforcing Pump, [Book VII, 

than in. large ones, becaufc the relative fur&ccs 
augment as the diameters diminifli. ThiJs> only 
for the expence, it would be wrong to makc^ as k 
commonly done, the raifmg pipe fmallcr than the 
body of the ^mp ; on the contrary, it would be 
better to conftru6k it of a diameter greater than that 
of the body of the pump, as the friftion would be 
proportionably diminifhed, ' 

The forcing fump is compofed of the body of 
the pump C D, (Plate VII Fig- 4-) flopped clofc 
at the bottom,' but entirely open above, and in 
which is a pifton If, which only differs from that 
of the pump already described in this, that its 
fucker S is placed at the bottom inftead of the topu 
This pifton, like that of the pump juft mentioned, 
is put in aftion by means of the lever Y X Z, 
which has its point of fupport in Z. The raiGng 
pipe A O is placed at the fide of the body of the 
pump, with which it communicates, and is furniih- 
ed with a fucker s in its lower part, and with a 
fpout O at its upper extremity. This pump, as 
well as the preceding, ought to be rmmerlcd in 
a well or bafon in fuch a manner that the body 
of ^he pump C D (hould be entirely under the 
furface of the water A A. 

The water fills the body of the pump by falling 
through the aperture C, and by paffing over the 
pifton K3 the fucker of it S, conG^ering its 
pofition, will naturally open. If the pifton K is 
lowered, by placing the lever Y X Z in the pofi- 
tion y u Z, the rcfiftance of the water againft the 
fucker S will clofe it immediately. Tbi? water 


.* Chap. 3*3 the fucking Puxtp. 505^ 

^' then, being incapable of rcpafling above the piftbn, 

is- forced up the pipe A O, by raifing up the fucker 

^ f. As foon as the pifton is raifed again, the fucker s hk 

^' dofcd by the preffur^ pf the water which is above, 

and the fucker S is opened by its own weight* A 

•: new mafs of water then piifles below the pifl:on> 

i^ which, by a fecond deprcflion of the pifton, is 

forced to pais, like the firft, into the pipe AO*; 

fo that by a pertain number of ftrokes of the 

pifton that pipe becomes full of water, which is then 

difcharged at the fpout O as in the pump already 

defcribcd. If the piftons in both of them are of 

the fame diameter, and the raifing pipes of the 

feme perpendicular height, the weight of the two 

columns of water will be equal, and the two 

pumps will r<*quire the fame power to work them j 

for in that cafe it requires the fame power to elevate 

the pifton charged with a column of water as it 

does to force the column of water with the pifton. 

The fucking* pump (Plate VIII. Fig. i.) is 
connpoled of the body of the pump EF, open abore^ 
and with a pipe of afpiration or fuckipg pipe F P 
adapted to the lower part. At the union of this 
pipe with the body of the pump is a fucker j, de- 
iigned to permit the water, while the pifton is raif- 
ed, to enter through the pipe of afpiration P F 
into the body of the pump F E, and to prevent it^ 
while the pifton is lowering, from being difcharged 
the fame way. In the body of the pump is ^ 

^ So called, becaafe it was originally fappo&d, bat errooe* 
pofly, to aft by fhftion. ' 

* pifton 

5o6 The fucking [BookVJi 

pifton L, made like that at I in Plate VIT. Fig. j. 

and which is put in adion in the fame manner by the 
afliftance of the lever X Z Y. This pump fbould 
be placed in fuch manner as to have only the lower 
extremity of the afpiration pipe F P plunged into 
the water. 

While the pump remains inadivc, the two' 
fuckers S and s arc naturally doled from their 
own weight. If the pifton Lis raifed up by meam 
of putting the lever X Z Y in the iituation u Z r, 
the colurfn of air which refts above is derated, 
and the air which is clofcd up in the afpiration pipe, 
from the furface of the water a to the pifton, 
having then more fpace to occupy, becomes more 
firified than the external air. This laft then preife 
more forcibly upon the furface of the water a, and 
caufes it to rife in the afpiration pipe, till the inte- 
rior air has regained its former denfity by occupy- 
ing lefs fpace. Thus, after feveral ftrokes of the 
pifton, the water reaches die body of the pump, 
and paffcs over the pifton, by raifingup the fuckers 
s and S, on? after another, and_ die pifton, by its 
fubfcquent elevation, forces the water to eicape at 
die fpout E. 

As it is the preflure of the air which caufes the 
water to rife in this pump, and as this prefliirc can 
iuftain only a column of water of about thirty -two 
feet, it is clear that the afpiration or fucking pipe 
fliould not exceed that length. In common pradice it 
}s indeed feldom made fo long as thirty-two feet. In 
^rder that the preffure of the atmofphere may be 
^ch as to fuftain a column of water of that height, 


Chap.j;] Pump. • 507 

It is ncceflary, firft, that the fucking pump fhoul4 
be made with the grcatcft exkctnefs, and that it 
Ihoiild continue in a perfeft ftate ; fccondly, that 
it fhould be placed upon the level of the fea, or 
very near it, becaufe it is there that the prcffure of 
the atmofphere is moft forcible j thirdly, that 
the prcffure of the air fhould not vary ; but in ge- 
neral all thefc' circumftances are not required. Me^.. 
ehanics are fatisfied,in general, with making the alpi* 
ration pipe twenty-three qr twenty-four feet long. IF 
it is'neceffary to elevate water to a greater height, 
the .forcing pump is more conimodious for that 
purpofc. The latter, it is true, is fubjeft to feveral^ 
inconveniencics. It is neceflary to place the body 
of the pump either in wells or in a bafon ; and 
when It is required to repair it, which often hap- 
pens, one of two things is neceffary, cither to 
empty the well or the bafon, or to draw up the 
body of the pump, which is extremely troublcfomc 
and expenfive. To remedy thefc inconveniencics, 
the beft and moft ufual mode is, when water is 
to be elevated from a great depth, to Inakc the 
pump at once both a forcing and fucking pump, iii 
the manner which f Ihall prefently explain. 

In the year 1766 it was reported, through the 
channel of the public papers, that at Seville, in Spain, 
afimple fucking pump had beonconftrudted, which 
elevated water to the height of fixty feet, and 
it was confeqticntly concluded, that the world had 
till then been notorioufly impofcd upon by the cur- 
Tcnt maxim, that the prcffure of the air could raifc 
a column of water only to the height of thirty-twe 

5o8 rbe/ucktng [Book VH 

ktx. M. BrifTon has carefully examined into the 
fa£fct and his expla^acion is curious and intcreft- 

An ignorant tinman, at Seville, had made a fiick* 
ing pump fixty feet long, becaufc he had occafioo 10 
elevate the water to that height. When the pucnp 
was Bxed in irs place, and put in aiSlion^ he was 
unable to make the water rife into the body of die 
pump. Enraged at this difappoiritment> l^ gave 
it a blow with his hammer, which produced a 
a fmall aperture in the afpiration pipe at about tea 
feet above the furfacc of the water in die bafoa 
Immediately a fmall portion of water arrived at the 
body of the pump. After this procels it was re- 
ported, that a fucking pump had been conftructcd, 
which elevated water to the height of fixty feet; 
but the reader will be enabled to judge of the truth 
of this aflertion from the following obtervatiofis : 

Let us fuppofe that the afpiration pipe, PF 
(Place VI 11. Fig. 1.) had from j, the fur&ce of the 
water of the bafon, to F, a diftance of fixty feet, and 
that after ascertain number of ftrokes of the piflon, 
the water rifes to c^ thirty-two feet high ; if thea 
a fmall hole is made at /», ten feet above the lur.. 
face of the water, the air which enters at this hole, 
and prefles in «ll direftioiis, will caufe the coluirn 
of water of ten feet, which is below ^, to &11 into 
the bafon, and the prcfllire of the ^ir upwards at 
i has only a column of water of twenty- two feet 
;o Support. 

But that preffurc is capable not only of raifiug 
|hat qolumn to. the height of fixty feet, but wen to 


Chap. 3.3 Pump. 509 

the height of eight thoufand feet j for air, dear the 
llirface of the earth, is eight hundred times left 
denfe than water, and foppofing (which is not the 
cale) it was not diminilhed in elevating, then the 
ten feet of water,, cut off by the preflure of the 
air at ^, downwards, would be more than equiva- 
lent ta eight thoufend feet of ain The column of 
air, therefore, which preffes at ^, will be too ftrong 
for more than eight thoufand feet; thus the 
twenty two feet of water remaining above will not 
be in equilibrium with the column of air till after 
it has rifcn higher than eight thoufand feet. 

In order to have a fecond portion of water with 
a pump of this conftruftion, it is in the firft place 
neceflary to ftop the aperture which was made at 
i, then to give feveral ftrokes with the pifton' to 
elevate the water as high as c 5 and laftJyj to open 
again the orifice at b. Obferve the fimplicity of 
this procefs for raifing fo fmall a quantity of water ! 
for it is neceflary that the afpiration pipe fhould be 
of a very fmall diameter, otherwifc the column of 
water would break, and the air would pafe through, 
and not one drop of water could be raifed into the 
body of the pump. This faft (adds M. Briflbn) may 
fervc to convince thofe who are fond of novelty, 
that before an opinion generally received is pro- 
nounced to be falfe, it is neceflary to think twice 
at the leaft. A ftiort time after the conflrufting of' 
this pump at Seville, M. Bellangc, a goldfmith in 
Paris, made one in imitation of it, to which he 
gave the additional property of throwing water 
fifty-five feet high, bymeans^of a continued^rf or 
• a ejedting 

5 1 p the fucking Pump. [Book Vtf ^ 

cjefting pipe> though the machine ,was only a 
£nipie fucking pump. 

To a fnnall bodied punnp oi two inches and 
oxie-twelfth in the interior diameter, the piftoa 
of whi^h had eight inches play, he adapted an 
afpiration pipe of ten-twelfUis of an inch dia- 
meter, and fifty-fix feet long; this^ipe was fiir- 
nilhed with a fucker at its junftion with tlic body 
of the pump, and with another at its lower extre- 
mity. This extremity was plunged into a tun fuB 
of water. M. Bellange had made a fmall perfla- 
tion in this pipe of about one twenty-fourth of an 
inch diameter, at twelve or fifteen inches above 
the furface of the water in the tun. The appa- 
ratus being difpofed of in this nmnner, he moved 
the f)ifton gently, but the water did not rile; 
the fmall hole furnifhed a fufiicicnt quantity of air 
to fill the a^iration pipe. He then moved the 
piflon with great velocityj the fmall hole could nori 
in fo fnort a fpace of rime, furnifli a fufficient quan- 
tity of air to fill the pipe^; a little water rofe and 
mixed itfelf with the air,- fo that the column be- 
came compofed of fmall cylinders, alternately of 
air and water, and though it was ififty-five feet 
high, it was much fhort of the weight of a column 
of water thirty-two feet high. If wc calculate, 
therefore, According to the diameter of the body of 
the purnp, and the extent in which the j ifton play- 
ed, what quantity of water this^pump woulJ have 
fiirnilhed if the air had not entered, and tlien com- 
pare this quantity with that wliich it really fumilh- 
cd, we fliall find tliat the latter is greatly inferior; 


Chap. 3.] ^be compound Pumf. J t f 

for in fix minutes five hundred and thirty (Irokes 
of the pifton . may be given, which would furmfh 
only thirty fix pints of water; this pump, .there- 
fore, would not furnifti the eighth part of the water 
which it ought to. do upon the comnfion principles 
of the fucking pump; (b that though the con^ 
ftruftion might a{)pear to be more ingenious, it was 
jK)t in reality to be preferred to that of Seville. 

The compound forcing pump is compofed of the 
body of the pump GH, (Plate VI 1 1. Fig. 2.) opea 
above, and the afpiration pipe H V adapted to the 
lower end. At the union of this pipe with the 
body of the pump is a fucker S, defigncd for the 
fame ufe as in the fimple fucking pump. In 
the body of the pump is a pifton M, not pierced 
as the preceding, but folid, and put in adtion by the 
aid of the rod x X, and of the lever Y X Z, which 
has its ix)int of fupport, or fulcrum, in^Z. At the 
fide of the pump, and towards the bottom of its 
body, is. adapted a raifing pipe H R, fiimiflied 
with a fucker s near its bafe, and with a fpout R 
near its fuperior extremity. This pump ought to 
be placed in fuch a manner that the lower extre- 
mity only of the afpiration pipe H V fliould be 
immerfed under water. 

It is eafy to perceive that the firft aftion of thts 
pump will be the fahie as, that of the fucking 
pump, which has been defcribed; for if the 
pifton M is raifed by putting the lever Y X Z in 
;he fituationj«Z, the column of air which refts 
above will be elevated ; the air which is in 
the afpiration-pipe will l^ecome, by thai means, 


jri The Fire [Book VI?. 

rarer than the exterior air. The latter then 
prcfies more forcibly upon the furfacc of the water 
A'Aj and carries it, afcer fome ftrokes of xht 
pifton, into the body of the pump ; when it h ar- 
rived there, if the pifton M is lowered, the fucker 
^S will ck>(c, and the water is forced along the 
raifmg-pipe H R, by the rifing of the fucker /, 
which, as foon as the preffure ceafes, falls agam 
•from its own weight and that of the water 
above it* 

This pump is very convenient, on account of its 
body being placed out of water, which affords an 
opportunity of making die neceffary repairs widi 
facility, and alfo on account of its being capad7ie 
of carrying water to any height which may be re- 
quired : in order to effeft this, all that is ncccffiry 
is, to lengthen the raifing-pipc, and to augment the 
power which puts the pump in aAion. I bdicvc 
this is at prefcnt the moft ufual forni of what are 
called forcing pumps in this country. 

The fire engine is an hydraulic enginr, wfiich 
may be claffcd with the pump that Thave now de* 
fcribcd. It is at once a fucking and forcing pump, 
but has a continued j^r/, orejefting pipe, though it 
has only one body. The effential parts of this 
pump are compofcd, like the coiTipoand pump, 
(Plate VII I. Fig. 2.) with this difference, that its 
afpiration pipe is much fliorter, and that inftead of 
a lolid raifing pipe it has a leathern tube of a con- 
venient length. This pump (Plate IX. I ig. i.) is 
then compofcd of the body of the pump A H, open 
above, and to the lower part is adapted the afpiration 




Fia. 2. 


Fuf / 

A - 

Chap. 3.] Engine 513 

H T. At the union of this pipe* with the body of 
the pump is placed a fucker S, defigned to prevent 
the waterj which has once pafled into the body 
of the pump> from returning into the bafon* In 
the body of the pump is a pifton M, not pierced 
but iblid^ ^nd which is put in mbtion by the aid of a 
metal rod x X, iuid of a lever Y X Z, which has 
its fulcrum or point of fup|)ort in Z. To- 
wards the bottom of the punnp, in the fide, is art 
aperture C, which is covered again by means of 
a valve r/, of wliich the tail / is the ipring, and 
Which is fixed on with a fmall fcrew. This valve 
fe defigned t6 prevent the water, which is expelled 
from the bodj^ of the pump, from entering again 
when the pifton M is raifed. The body of the pu^p 
is furrounded with a pipe A B D £, about two or 
three inches more in diameter than the body of the 
i}ump, and die intermediate fpace between them 
ii filled with air. To the lower part of this pipe, 
and upon the fide, is adapted another fmall crooked 
J>ipe E R^ furniftied at the end R with a fucker x, 
and with a fcrew ferule, receive a nut^ 
by means of which the leathern pipe is joined to 
this end of the engine, and which ferves inftcad of 
the raifing pipe in the confimon forcing^ pump. 
All this apparatus is placed (as may be feen in 
Plate IX. Fig. a.) upon a box or cafe NO lin- 
td with lead, which contains the water. The crofs 
bar QJupports the upper end F (Fig. i.) of the 
body of the pump, which, for that purpofc, 
is of a fmaller diameter than the reft; and the lid L 
(Fig. 2.) of the box has an aperture in the middle. 
Vol. II. LI to 

514 rbeFire [Book VIL 

to admit the alpiradon pipe H T to pals through 

From this explanation it will be evident* that if 
the pifton M is railed up by putting the lever 
YXZ in the fituation jr«Z, the fucker s and the 
valve f, placed in C, wi)l be clofcd by the preflure of 
the exterior air. This fame preflure, exerciling its 
force upon ihc furfece of the water V V, obliges 
it CO pafs into the body of the pump by taifing up 
the fucker S. It then a£ts as a fucking pump ; but 
when the pifton M is lowered, its preffiire doles die 
fucker S, and opens the valve which is in C ; die 
water then pafles, not only into the leathern pipe 
abd, (Fig. a.) by railing up the fucker i (Fig, i.) 
but alfo into the fpace between the body of the 
pump and the pipe which mclofes it, by riling to- 
Wards I K, and comprefTes the air which is confined 
there. Immediately after the pifton M is raifixl 
again, that air, being no longer comprefled, unfolds 
itfelf by its elafticity, a£b upon the water which is 
between the body of the pump and the pipe which 
incloied it, and forces it alfo into the leathern pipe, 
fo that when the pifton is loweredi the water is 
forced by the pifton itfelf, and when it is raifed, the 
water is forced by the elafticity of the air, which 
furniflies a continued ftream, though the pump has 
only one body or principal cube. 

It is evident that thefe fire engines fhould be abia 
to fumifh a continued ftream, and this can only be 
efFefled by employing the elafticity of the air, while 
the pifix>n b riling ; but in order to effed this, adoublc 
force is required to put the pump in motion i in 



Chap. J.] Effgin^l 5 1^ 

o^her wordsj ^ force capable of expelling the columii 
of ^vaterj, and an equal force to compref$ the air. 
But this is not an inconvcfiience, fpr^ in cafe qf fire, 
it very feldprii happens that hands ar^ wandng to 
aiXifl^ on ?he contrary,, it frequendy happens that 
the aflemblage of people is rather too numerous. 

Such is the engine which M. Briflbn has defcrib- 
ccj, and it is, I prefume, that which is in ^commort 
ufc in. France. Its fimplicity is admirable ; yet I 
apprehend that our Englilh fire engines are more 
powerful, and,furnifh i^. more uninterrupted flrearxi 
or current of water thrdugh the leathern pipe. 
In Fig. 3. IS a rcprefcntation of pur im- 
proved fire engine. This, the reader will fee, is 
wrought by two forcing pumps, which aft ^ternate- 
ly ; and the ftream is made continual from the 
fpring of air confined iii a flrong metal ireflel C C, 
in the fire engine AB, fixed between the two 
forcing pumps D and £, wrought with si, comnion 
double lever FO moving on the center H. The 
piftons in D and £ both fuck, and force alternately^ 
and are here rfcprefented in their different aftionsi 
as are alfo the refpeftive valves at I K and L M. 

The water to fupply this enginci if there is no 
opportunity of putting the end of a fucking pipe, _ 
Occafionally to be fcrewed 6n, into a moat or canal 
(which would fpare much hurry and labour in cafe 
of fire) is poured into the veiTel AB; and being 
ilrained through the wire grate N is, by the prdTure 
of the atmofphere^ raifed through the valves K and 
' M into the barrels of D or £; when either of their 
forcers afcend; whence again, upon their defcent, it 
• LI 2 wiU 

5 16 the Fire Engine. [Book VII. 

wiH be powerfully propelled into the air-veflH 
C G, through ' the valves I and L by tnrns : the 
common- atr then between the water and the top 
of the air-veffel C C will from time to time be for- 
cibly crowded into lels pootn^and much compreffed ; 
and the air being in t*hat condcnfed ftatc poffefled of* 
a ftrofjg and lively fpring, and always endeavouring 
to dilate itfelf every way equally in fuch a circum- 
ftance, bears ftrongly both againft the fides of the 
veflel wherein it is confined, and the furfacc of the 
water thus injeftcd ;• and thus produces a conftanc 
regular dream, which rifes through the metal pipe 
P into the leather one Ch and this latter- being per- 
feftiy flexible, may be fed about into rooms and 
entries, as the cafe may require. 

Should the atr contained in this veflel be com- 
{)reflfed into half the fpace it took up in- its natural 
ftate, the fpring of it will be nearly dou- 
bled ; and as bl^fOre it equalled and wa$ able to 
fuftain the prcflure oi the atmofphere, fmce it has 
now a double force, by the power o{ that fpring 
alone it will throw water into air of the common 
degree of denfity about thirty feet high. And 
Ihould this compreffure be ftill augmented^ and the 
quantity of air>- which at firft filled the whole vcffil^ 
be reduced into one-thiixl of that fpate, its Jpring 
will be then able to reftft, and cOnfcquently to raift 
the weight of a treble athiofpherc$ in which cafe 
it will throw up a jet of water fixty feet hi^. And 
fljould fo much water again be forced « into .he 
veflel as to fill three parts of the capacity, . it will be 
able to throw it up about ninety feet high : and 



Maie 9 

Chap. 5.] Modes of working Pumps. 517 

wherever the fervice fliall require ^ ftill greater rife 
of water, more water cnuit be forced into this 
vefiel i the air therein being thus driven by 
.force into a ftill narrower compafs, at each ex- 
f>lD(ioii, its gradual reftitution to its firft diaien^- 
iions is what regularly carries on the ftream be- 
tween the ftrokes, and Fenders it continual during 
the operation of the wiachine. 

Various agents are employed to put pumps in 
aftion, fuch as men, horfes, ftreams o( water, va- 
pour, wind, &c. Small pumps, fuch as thofe in 
common wells, or fire engines, are generally 
wrouight by men. When a confiderable quantity 
of water is required to be railed, the moving power 
muft be increafed I . and in order that a regular 
effort may be employed, or very nearly fo, feveral 
additions are occafionally made to the mechanifm of 
pumps, fo that when one fet*of piftons defcend an- 
9ther fet may be made to j-ife by the f^m^ force. 
The great engine at Marli is wrought 'by an appa- 
ratus of this kind. ' 

The aftion of thefe engines depends upon the 
regularity of the altcrn?ite motion of the fuckers or 
valves. It follows then, that thefe ilhould be fo 
conftrufted and difpofed as perfedly tio retain the, 
water when they are clofed, and to open eafily when 
the aftion of the machine is diredfced to that objeft^ 

V. Of the motion of wWer in conduit pipes. 

When it I is requtred to conduct water from 
one place to another, it is very clear tlhat the con-r 
duiiing pipds muft be longer than^he fJ)acexhrou^ 
whichi it is to be conveyed. 

L 1 3 In 


Motion of Fluids ibrougb [Book VIL 

In treating of the difcharge of water throi^ 
additional pipes, I have takdi but a curlbiy notibe 
of the refinance by friftion, becaufe there it 5 
fcarcely perceptible ; but it is not the lame witfc 
reiped to pipes of coiiiliderable extent ; the fri^oo 
of the watter againft their' fides leflens confider- 
ably the velocity of the flowiiig water, as Has been 
proved by experiments. I fhafl fitft Ipeak of refiS- 
hnear pipes. 

In the following experiments two pipes were 
employed, one ofan inch and a qiiartef diamete^ 
and the otheV of two inches. ' The two pipes weri 
fucceflively lengthened' from thirty feet to one 
hixndred and eighty ; and the cohftant height of the 
Water In the refcrvoir, abovfc the pipes, was Ibrne* 
times one foot, and fbmetinies two; • - 
^ 'The following table (hews the refults of thcfi; 

The conAant 
water in the 
aboy^ Ihe 
pipe, in inches 

The diftance to 

wi^er was con- 
veyed, exprefled 

. ip^e^ct.-.' 

The miraher of 
cuVic inches of 

in one miniMe, by 

a pipe ofan ind) 

and a garter 


The number of 
cable iiKbeiol 
water famiflied 

a pipe of two 
inches dianoecer* 

* * ■ » 


• 1778-*-* 

■ 76«o * 










iSO . 











. 60 




















Chap« 3.] CtmduU Pipes. 51^ 

If^ by the aid of the table of additional pipes, 

which has been before infert^d, we fhould wifh to find 

the quantity of water difcharged by two additional 

^ipes of one inch and one-third and two inches 

diameter, under the fame height of the refervoir, 

and without having any regard to friftion, but only 

to the areas of the orifices of the pipes, it will be 

found, that during one minute, 

1 • The height of the rcfervoir being one foot, the 
pipe of one inch and one-third diameter, in this 
cafe there will be difcharged fix thoufand two hun- 
dred and ninety-two cubic inches of water. 

a. The height of the refervoir being two feet, 
the fanie pipe will furnifh eight thoufand eight hun« 
dred and ninety-three cubic inches of water. 

3. The height of the refervoir being one foot, 
and die pipe two inches in diameter, there will be 
difcharged fourteen thoufand one hundred and fifty- 
fix cubic inches of water. 

4. The height of the refervoir being two feet, the 
fame pipe will furnilh twenty thoufand and eight 
cubic inches of water. 

It is eafy to perceive, that thefe quantities of wa- 
ter are much greater than the correfponding quan- 
tities in the above table; ai;id that the quantity 
fumiftied by each pipe diminiflies, in fad, in pro- 
portion to its length, becaufc there is then a greater 
furface of fridion. But it muft be remarked, that 
the diminution of the quantity of water difcharged 
is not exadly in proportion to the length of the 
pipe. Thcdifcharge is indeeddinrjinifhcd as the 
pipe is made longer; but this diminution decreafea 
LI 4 (if 

5 20 Bifchargi of Water [Bo6k VII. 

(if I may ufe die «prcffio«j) in the progrefs q£ the 
current 5 for the firft thirty feet the difcharge is 
diminilhcd much more than in the fecond thirty 
feet ; and the third augmentatioh of thirty feet to 
the length diminiflies the difcharge ftillleis than the 
fecond ; and fo of the reft. The rcfult of all this 
is, that in common praftice, wherp great precifion 
is not required, it may be laid down as a rule, Astt 
die quantities of water difcharged in equal naiss^ 
through the fame horizontal pipe, under thp fame 
height of the refcrvoir, and at different dillances 
from the fource or refervoir, arc to each other 
nearly in an inverfe proportion of the fquare roots 
of thefe diftances. 

It may be obferred from the preceding table^ 
that a pipe of one inch and one-third diameter fiir- 
nifties left water in proportion than one of two inches 
* diameter, under the fame height of the refervoir^ 
and of the fame length. The reafon of this is, bc- 
caufe there is, relatively to the quantities of water 
which thefe pipes will contain, more furface of 
friftion in the fmall pipe than in the larger one. 

If the fame pipe was curviHnear inftead of being 
ftrait, the difcharge would ftill be diminifhed from 
this circumftance, though not in any confiderable 
degree ; but the diminution would be ftill greater if 
the curvilinear pipe was placed in a vertical inftead 
of a horizontal pofition. The diminurion (linall as it 
is) is produced by the refiftance which the water 
meets in running againft the an^es of the pipe, 
* which deprive it of a part of its velocity. 


Chap« 3.3 through Candmt Fifes. $%% 

But if the pipe, inftpad of being curvilinear, wa^ 
angular in feveral points^ the diminution would be 
greater^ and the more fo in proportion as rhofa 
angles (hould be nnorc acute, bccaufc then the rc- 
fiftance %o the water would be more dircft. When 
the pipes are curved, and their curvature vertical, 
as in Plattt^X. Fig. i. there are then declivities and 
afcents in which the air will lodge, and refill or even 
impede the courfe of die water. For example, 
let ABCDEFG be a pipe, die upper ex- 
tremity of which A anfwers to a refervoir which 
fupplies it with water, and the extremity G goes to 
furnifh a fountain. The pipe being filled with 
nothing but air, and water being made to run from 
A, this water will drive the air before it, and fill the 
portion of the pipe A B more than the portion BCi 
the water haying arrived at the bending G, will flow 
down the lower part of this bending, and will pro- 
ceed to fill the bending D, leaving behind it the 
column of air C D, which cannot efcape. The wa- 
ter, continuing to run, will rife from D to E, and 
having arrived there, it will ftill flow down the 
lower part of this declivity to fill the bent F, leaving 
behind it a fccond column of airEF, which will re- 
main confined there, notwithftanding the preflure 
of the colymn AB; for the column of air CD 
canpot counterbalance the prefl!ure of the column 
of water D E, any more than the column of air E F 
is capable of counterbaliancing the column of water 
F I ; fo that though the water in the pipe' A B is 
confiderably above the level G, the water can only 
fife towards I^ and there ceafes to flow. The only 



522 0/ciUatory Motion of Water [Book VIL 

remedy is, to let out the two cdumns of air CD and 
E F, by placing at the elbow of the bendings two 
fmall pipes C and £, through which the air may 
efcape, and when the courfe of the water is wdl ar- 
ranged the apertures may be clofed with bungs. 

VI. Of the ofcillatory motion of water in a 

It is well known that the duration of the olcilla- 
tions of two pendulums of unequal lengths are to 
each other as the fquare roots of thoje lengths^ 
The ofcillatory motion of water in a lipbon is of the 
fame nature, 

Suppofe a fiphon (Fig. a.) compofed of three 
branches, two verticle 7;^, mo^ and one hori- 
zontal n a ; fuppofe that the interior diameter of 
the fiphon is equal through its whole extent; diat 
in this fiphon^ the fluid, in a (late of reft, occu[hcs 
the {p^cc anod', then the two furfaces^^, cd^ ase 
upon a level. Suppofe then, that, by fbmc caufe, 
phe liquid is forced to defcend to g i, in the branch 
Iff a, and confequently to elevate itfelf to tf/, in the 
branch /;;; as foon as this caufe ceafes to a6t, the 
fluid will be operated upon merely by the comnnon 
laws of gravitation and motion. The exceis of the 
length of the column e n, above that of the column 
b 0, will force the fluid to defcend, and that even 
belo)v the level of the other, on account of the 
ac(;eiefapon of its defcent, which will caule the 
fluid in the other branch mo to rife; the fluid will 
then defcend and afcend alternately, or in ofcilla- 
pons fimilar to thofe of a pendulum $ and the devi- 
atipn of each of thefe ofcillations will be precKbly 


^hap. 3.3 in a Sifhm^ vnd m Warnu 523 

tthe fame as that of the ofciSations of a penduh^m 
^alf as long as the length p q r of the column of 
the ftuid. 

Snce the ofcillations of water follow the ianne 
law as thole of a pendulun), it follows, that if th^ 
length of the column of water is augmented or di- 
'jninifhed, the duration of each oicillation will be 
'augmented or diminiflied 

VII. The ofcillatory motion of water in waves 

has been compared by Sir Ifaac Newton * to the 

oicillatory motion of water in a fiphon. 

^ Let A B C D E F (Fig. 3.) be fuppofed a flieet 

of water, the fiirface of which rifes and falls in fuc- 

ceffive waves ; let A C E be the tops of thcfc waveSi^ 

and B D F the intermediate hollows or concavities, 

which leparatc'tliem. As the waves are formed by 

the fiicceffive afcent and defcent of the water in fuch 

a manner that the higher parts become the lower, 

and fo altemaicly and fucceflively, and as the 

weight of the elevated water is the moving power 

which caufes the lowed parts to afcend and the 

higheft to defccnd, thefe alternate rifings and falU 

ings are confidered as analogous to the oicillatory 

modon of water in a fiphon; and they obferve the 

fanie laws relative to their duration^ 

If there is then a pendulum, the length of which b 
equal to half the tranlverfal diftance that exifts be* 
'tween the top or apex of a wave A (for example) 
and the cavity B, that is equal td half A ^, the 
htgheft parts will become the loweft in the fame 

• Principia, lib. z> prop. 46* 

' - • fpacc 

524 MQtim^lVmts. [BookYIL 

rpacc of time in wbicfa this pendulum vifaralc^ 
^nd in the fpace of another oicillacion they will ag^ 
become the higheft. Each of thele waves cbeB 
will roll its whole courfe during the time which the 
pendulum takes in "performing two oAnilations; 
and as a pendulum four times the length of the 
precedingi that isj the length of which is equal to 
the width of the wave A C, will make only one 
ofcillation, while the firft makes two, it follows, 
chat the waves . perfbrn) their oicillations in the 
fame fpace of time as a pendulum equal in lengdi 
to tl^ width of the fame waves would perform its 
ofcillations. What is meant by the width of wa^vc, 
IS the tranfverfal fpace .A C, which is between their 
greateft elevations, or the fpace ^ B D, which is be- 
tween their greateft concavities. 

It follows from thefe premifes, that waves, which 
are about three feet and three quarters of an inch 
wide, roll their whole width during a lecond of 
time, and confequeotly they roll one hundred aixi 
eighty-three feet fix inches and fiv^e-fixths in a mi- 
nute, and in an hour eleven thoufand and fouixcen 
feet two inches; waves four times as wide will 
roll this fpace in twice the time; it follows then, 
that the wider or more expanded the waves are, 
the greater will be the fpace which they will roll 
over in a given time. 

But what has now been ftated rcfpedting the 
morion of waves> is founded upon this hjrpothcfis, 
that all the parts of the water rife and fell in right 
lines ; yet it muft be obferved, that both their rife 
and fall are more frequently made in curved lines 
4 than 

ChJap. 3.] • • H^at& tweets. 52^ 

t!han iii ftrait oncs> fo that the determination given 
afeove refpefting'the fpace which waves roll over iiv 
a* given time tnay be regarded only as an approxi* 
iTtation CO the'trath* ,. . ; 

/. .VIII. The nK)tiojft of .wheels afted upon by the 
fall or force of water, though ft^^iftly a branch of 
TOCchtnics, h yet btimately connected with the 
Iciejice of hydraulics. 
-The wheels of fome water-niilljs arc furniflied 
"With wings, float-boards, or (helves, at their cir- 
cumference, with very little or no concavity 1 
others arc ferniihed with a kind of ladles or boxes, 
vhich will contain a confiderable quantity of water. 
In the firft cafe, the water afts upon the wheels 
principally by its. (hock or fall j in the. fccond, by 
k^3we}ght. I ihall firft fpeak of wheels moved by 
, the (hocksr of (;he water. 
. It Jias been proved by experience, that the more 
numeroiis the wings or float-boards are inproportion 
to the diameter pf the wheel, the fafter it moves. To 
wjieels of twenty feet diameter, there are commonly 
placed about forty float-boards j but agreater number, 
as for example forty-eight, wouki be ftiU more ad- 
vantageous. To the. wheels of thofe mills which arc 
iraifcd upon boats or rafts in rivers, there are ufually 
only eight or ten floats; but thefe wheels would 
have more efFeft if they had fifteen or fixteen. 

When a wheel with wings or float-boards turns 
in a kind of frame or cafe, fo as to prevent the 
water from falling immediately into the general 
current, the impulfe which it receives from the wa- 
ter is about one-fifth greater in proportion to tlie 


5^6 C^fimaimof [BdokVII; 

velocity of the fluidi than it would receive in lA 
snconfined ftreani, becaufe in die latter cafe die 
"water which abounds is turned behind die floa^ 
and reGfts it; on the conczarjri wheiLtfae whcd 
moves in a frame, diere b only a finall quaiuity of 
water, which nioves with as much vdodty^ of wkh 
' . rather more, than the float- board. 

Ic has been proved by experience, that when tBb 
cafe or frame is but juft wide and deep enough tof 
admit the wheel tio move freely, and the water ius 
an opportunity of running nut after having given as 
ihock or impulfe, the dirc£b and perpendicular force 
againfl the floats of the v^^licel is about twice the 
force which the float would receive if it was plunged 
to the fame depth in an unconfined current. 

When a wheel furnifhed with forty-eight floats 
turns in a cafe or frame, and it is not plunged very 
deep in the water, its circumference will have aboui 
two- fifths of the velocity of the current, iri wliich 
cafe the machine will produce the greateft efieft. 

It appears that float-boards are the moll advan- 
tageous when they are placed in a direft line 
towards the center of the wheel; becaufe but 
few of them would be required, fince they would 
then be fhuck perpendicularly by the water, which 
^ produces the mofk powerful cJFcft^ When they 
incline, the fhock is oblique, which diminifhes the 
effort; yet a certain degree of inclination canfes 
the water to rife the length of the float, and to re- 
main^thtre a certain time ; it then ai&s by its. gra- 
vity after having a£fced by its (h()ck or &], and 
the efl[e£t which refults from d;iis arrangement more 


Chap. 30 ^^^^ Wheels. . . 547 

than compenfates for the diminution which the 
fliock foflFered fronn the. obliquity with which the 
force was applied in the firft inftance. In general, 
the wheels placed in franies which have a certain 
declivity (hould have their floats or bucket;3 inclined 
fo much towards the radius as to caufe them to be 
ftruck in a more perpendicular 'direftion, that they 
may receive an augmentation of force from the 
weight of the water.' The moft advantageous in- 
clination of the floats towards the radius appears 
by experience to be between twenty and thirty 

A wheel pla<xd near a rcfervoir turns fwifter 
than in any other place, becaufe then the whole 
force of the defccnding fluid is efFcftuaUy applied ; 
but if there is a necefllty for placing it at the end of 
the water- courfe, at a certain diflance from the 
refervoir, the channel of the water-courfe or frame 
Ihould incline about the tenth part of its length, fo 
that the floping may give to the water that degree 
of velocity which would otherwife be dcflS-oyed by 
fri£tion 5 die wheel will then receive the fame im- 
pulfc as if it was placed clofe to the refervoir. 

Water afting by its weight produces a much 
greater tSt& than when it a6b by its fhock in fall* 
ing. M. Parent, in the year 1794, and M. Pi^^ot, 
in 1725, indeed demonftrated, that a whed! (fup- 
pofcd to be without fridtion) moved by a current 
of water, and defigned to elevate a portion of that 
water to the height of that which puts it in motion, is 
incapable of elevating it higher than tt or ^ .nearly ; 
whereas the water afting upon the wheel by its 


5<z» tf^ater irheels. [BookVIl. 

own weight would be capable of ekv^adng to die 
height from which it defcended half of the water 
which defcended. 

When, therefore^ we have only a fmall qaandrr 
of water, and are obliged to hufband it well (whic& 
often happens, becaiife there are more fmaU ftrcams 
than large rivers) we fhould contrive to make ths 
water a£b by its weight rather than hj its fhodk 
orimpulfe; for this purpofe, inftead of haviqg 
wheels with plain float-boards, they fhould be for* 
niftied with concave or hollow ones refembliig 
buckets, whenever we can have a fall of more than 
four feet, and efpecially where *here is ^€A the 
neceiTary quantity of water to turn a mill with 
wheels, furniibed with plain float-boards. 

M. Deparcieux, in the Memoirs of the French 
'Academy of Sciences *, has proved, that the flower 
wheels with buckets move, the more will be their 
effeft with an equal expence of water. He made a 
fmall wheel of twenty inches diameter, the drcum- 
ference of which was furnifhed with forty- eight 
buckets. Upon the axis of this wheel were 
placed four cylinders of diflTereot fizes ; the leaft 
was one inch in diameter, the next two inches, 
the third three inches, and the fourth was four 
inches in diameter. Thefe cylinders were different 
axes, afcout which a cord, which elevated a weight 
by means of a returning pully placed above the ma- 
chine, wrapped itfelfl The axis of the wheel was 
fupported at each end by two rollers eafily pui m 

• Far the year 17541 page 605 and 671 • 

motion I 

t ^ 

Chap. 3.] Experifnents on Water Wheels. 515 

TOotion J this was to diminifh the fridKon. To the 
fore part of the wheel, and a little higher than its 
a^isj was attached a fmall flielf^ upon which w^ 
placed a veffel with a hole pierced in it on that fide 
towards the wheel, which was filled with water. 
Above this veffel was placed a large bottle. fijll of 
water inverted, and the neck of it was plunged a 
few lines in the water of the veffel, in order that 
the bottle fhould only empty itfelf in proportion as 
the water in the veffel ran through the aperture. 
The water in flowing fell into a channel which car- 
ried it into the buckets of the wheel By this means 
he made fure of employing, at each experiment, 
always the fame quantity of water. 

The following table cqntains the rcfults of the 
experiments made by M. Deparcieux. He fome- 
times elevated weights of twelve ounces, and fome- 
times of twenty-four ounces: the heavieft, refitting 
the mod, compelled the wheel to turn flower. He 
wrapped the cords which fupportcdthc weights fuc- 
ccffively- round the different cylinders, and found 
that the fame weight refiffed fnbre in proportion as 
its cord was wrapped round a lai'ger cylinder. 

Diameter of the cy- 

I Inches. 


Elevation pf a weight 
■ ofiz/bunces. 

69^ Inches. 



weight of 34 







Sp tf^aier Wbeetsi [BookVIL 

. Wten the cord was trapped round a larger 
cylinder, or the devatcd weight was more confi- 
derable, the wheel turned flower. It appears from 
thcfe rcfults, that the fame weight was carried fb 
much higher according as its cord was wrapped 
round a larger cylinder. It appears alfo, that douUe 
the weight which retarded the rotation ftill more, 
was carried to more than half of the height to which 
the fingle weight was carried ; in that cafe, there- 
fore, the cfFcft was grcaten 
. It may be laid down as a principle, that water 
afts by its weight much more forcibly from the 
lame height or fall, than by its impulfcs and that 
the flower wheels with buckets move, the greater, 
with the fame expence of water, will be their efitcL 
This augmentation of efFedt is caufed by the fimc 
quantity of water ading longer^ while the whe«l 
moves with lefs velocity. 


Chap. 4.1 t 531 1 

C H A P. IV. 


Saltne/s o/tbi Ocean^ — Dijffirmt Opinions as to the Cau/i^^^Proiai^ 
^tqfims njohy the Sea has been alnvays Jalt. '^Temperature of the 
Sea at different Depths ^'^-Modes of rendering Sea-nvater frfjffi, 

THE greateft quantities of water with which 
we are acquainted arc by no means pure» 
but united with faline matter. The ocean is fait 
in all parts of the world j but the degree of faltnefs 
diflFers much in different cli; nates, and is alinoft 
univerfally found to be greater in proportion as the 
water is taken up nearer the equator, • where the 
heat of the fun is greateft, and the evaporation of 
the watery particles confequently more confiderable. 
When treating of fea fait, the refult of various obfer* 
▼ations relating to this fubjed were detailed. 

The caufe of the faltnefs of the ocean has been a 
fubjedt of inveftigation among philofophers in al- 
moft all ages, but it ftill remains in great obfcurity* 
There can be little doi ^t, that a large quantity of 
faline matter exifted in this globe from the creation i 
and, at this day; we find immenfe beds of fal gem, 
or common fait, buried in the earth, particularly 
near Cracow j but whether thefe coUedtions have 
been derived from the ocean> and depofited in con- 
iequence of the evaporation of its waters in certain 
M m 2 circum-* 

j>i Sdltnejs if - [Book VIL 

circumftanccs, or whether the ocean was itfclf 
originally frefti, and received its fait from collec- 
tions of falinc matter (icuated at its bottom, or from 
that brought by the influx of rivers^ cannot now be 
afcertained. No accurate obfervations on the de- 
gree of faltnefs of the ocean in particular latitudes 
were mad^ till the prefent century, and it is tM 
poflible, therefore, to afcertain what was thfcftaieoi 
the fea at any confiderable diftance of time, nor, 
confequently, whether its degree of faltnefs in- 
creafes, dccreafcs, or is ftationary. From difiercnccs 
among aquatic animals, however, fome of whidi 
feem adapted to fait water, and fome to frcfh, it is 
probable, that both thefe ftates of water cxiflccf 
from the creation of the world. We know it is 
true, that fome kinds of fifh, as ialmon, are capable 
of cxifting both in frcfli and in fait water, and th«t 
habit has a powerful influence over all animals; but 
this is not fulBcient to refute the main fa6t, thit 
fome kinds of fifh thrive only in fait water, others 
in frcfh j fome in {landing pools, and others in rapid 

' That excellent philofopher and chemift, to whole 
labours I am indebted for fome of the mod va- 
luable parts of thefe volumes, the bifliop of Landafi^ 
has recommended a moft fimple and eafy mode of 
afcertaining the faltaefs of the fea in any latitude? 
and as the language, in point of pcrfpicuity and cor- 
rednefs, cannot be Improved, I (hajl take the liberty 
of inferting it in his own words. 

* As it is not every perfon who can make himlclf 
*pert in the ule of the conomon menns of eftimat- 


Chap. 4.] . the Ocean. 533 

ing the quantity of fait contained in fea water, 1 
will mention a method of doing it, which is fo 
cafy and fimplc, that every coninnon failor may 
underftand and praftife it, and which, at the fame . 
time, from the trials I have made of it, feeais to be 
as exaft a method as any that has yet been thought 
oC — Take a clean towel or any other piece of 
cloth, dry it well in the fun or before the fire, tlien 
weigh it accurately, and note down its weight i dip 
it in the fea water, and, when taken out, wring it a 
little till it will not drip, when hung up to dry^ 
weigh it in this wet ftate, then dry it either in the 
fiin or at the fire, and, when it is pcrfeftly dry, 
weigh it again. The excefs of the weight of the 
wetted cloth above its original weight, is the 
weight of the fea water imbibed by the cloth ; and 
the excefs of the weight of the cloth, after being 
dried, above its original weight, is the weight of the 
ialt retained by the cloth ; and by comparing this 
weight with the weight of the fea water imbibed by 
the cloth, we obtain the proportion of fait contained 
in that fpecies of fea water. 

^ Whoever undertakes to afccrtain the quantity 
of fait, contained in fea water, either by this or any * 
other method, would do well to obferve the ftate of] 
the weather preceding the time when the fea water 
is taken out of the fea, for the quantity of fait con- 
rained in the water near the furface may be influen- 
ced both by rhe antecedent moifhare and the an- 
tecedent heat of the atmofphere ♦.' 

Whether the fea is falter or not at different 

* Wation's Chemical SfTaySf vol. ii. p. 116. 

M n) 3 depths 

534 ^emperaiure of the Ocean [BookVIIr 

depths has not yet been afcertained; but that its 
temperature varies confiderabiy in proportion to the. 
depth we have decifive proof. 

* With, refpeft to the temperature/ fays bilhop 
Watfon, * of the fea at different depths, it feems 
reafonable enough to fuppofe, that in fummer time 
it will be hotter at the furface than at any confider- 
able depth below it, and that in winter it will be 
colder. Suppofc a ciftern, twelve feet in depth, to 
be filled with fpring water of 48 degrees warmth, 
to the height of eleven feet; then, if we fill up the 
ciftern to its top, by gendy pouring water heated to 
1 00 degrees upon the furfece of the fpring water, it 
may readily be underftood, that the heat of this 
water will not be inftantaneoudy communicated 
through the whole mafs of water in the ciftern, but 
that the water will decreale in heat fronn the furface 
to the bottom of the ciftern. On the other hand, 
if on the 1 1 feet of fpring water heated to 48 de- 
grees, we pour a foot of water heated only to ^3 de- 
grees, it may be expe<fted, that the fpring water, 
V^hich is neareft to the cold water, will be fooner 
cooled by it than that which is at a greater diftancei 
and on this account die water at the bottom of the 
ciftern will be warmer than that in the middle or a( 
the top. It muft be obferved, however, that cold 
water being, bulk for bulk, heavier than hot wa- 
ter, the water which has only 33 degrees of heat 
will defcend, by its fuperior weight, into the mafs of 
water contained in the ciftern, and thus the water in 
the ciftern will be cooled, not only by the bare 
<:ommunication of cold from the upper water, but 


Chap. 4*] at diffennt Depths. 53S 

by the aftual mixture of that water with the reft, fo 
that the difference between the heat of the water at 
the bottom and top will not b^ fo great as it would 
have been if" the cold water had not mixed itfelf 
•with the reft. Thefe fupppfitions of hot jind cold 
water incumbent on the fpring water in the ciftern^ 
are analogous to the aftion of the fummer and win- 
ter atmofpheres incumbent on the furface of the fea. 
No perfon, who has bathed in deep ftanding water 
in fijmmer time, can have failed to obferve, that the 
water grew colder and colder, according^ to the 
depth to which he defcended. I have frequently 
oljferved, that the furface of a pool of water of two 
feet in depth, has in a funny day, even in winter, 
been five degrees hotter than the water at its bot- 
tom. . : 
^ Mr. Wales defcribes the inftrument he made 
life of for trying the temperature of the fea at dif- 
ferent depths, in the following terms ; " The appa- 
latus fqr trying the heat of the fea water at difl^renc 
depths confifted of a fquare wooden tube of about 
18 inches long and three inches fquare externally^ 
It was fitted with a valve at the bottom, and ano« 
ther at the top, and had a contrivance for fufpend-r 
ing the thermometer exa<aiy in the rniddlc of it. 
When it was ufed it was faftened to the deep fea 
}ine, juft above the lead, fo that all the way as it 
^ defcended the water had a free pafTage through it, 
by means of the valves which were then both open^ 
but the inflant it began to be drawn up, both the 
Yalves clofed by the preffure of the water, and of 

M m 4 f ourfc 

5^6 Temperature of the Otem [Book V\l. 

courfe the thermometer was brought up in a bodf 
of water of the fame temperature with that it was 
let down to*." With this inftrument, which is much 
the fame with one formerly defcribed by Mr. 
fioyle> in his obfervations about the faltnefs of the 
fta, water was fetched up from different depths, 
and its temperature accurately noticed^ in difirrcnc 
feafons and latitudes. 

' Auguft 27, 1772, fouth latitude 24*. 40^ The 
heat of the air was 724^,— of the water at the fur&ce 
70, -of water from the depth of %o fathonis 
6b f. 

* December 27, 1772, fouth latitude 58*. ?i^ 
T!)\t heat of the air was ji ,— of the water at the 
furface 32,— of water from the depth of 160 &- 
thorns 33 i- J. 

^ In the voyage to the high northern latitudes 
before mentioned, they made ufe of a bottle to 
bring up water from the bottom, which is thus de- 
fcribed. " The bottle had a coating of wool, 
three inches thick, which was wrapped up in an 
oiled ikin, and let into a leather purfe, and the 
whole inclofed in a well-pitched canvas bag, firmly 
tied to the mouth of die bottle, fo that not a drop 
of water could penetrate to its furface. A bit of 
lead fhapcd like a cone, with its bafc downwards, 

* See Aflronomical Obfervations made in a Voyage towards 
the South Pole, &c. in 1772, 1773, &c. by W. Wale?, hii 
trodadion, p. 53. 

t Wales' Obfcn p, 206. 
\ Jbid. p. ^o8. 

Chap. 4.] at different Depths. S37 

and a cord fixed to its fmall end, ivas put Into the 
bottle^ and a piece of valve leather, with half a 
dozen flips "of thin bladder, were ftrung on the cord, 
which, when pulled, efFeftually corked the bottle 
on the infide.**, I have here put down two of the 
experiments which were made during that voyage. 

• Auguft 4, 1773, north latitude io\ 30^ The 
lieatoftbeair was 3:, --of the water it the furfacc 
36,— of water fetched up from the depth of 60 
fitthoms undcl" the ice :J9*. 

^ September 4, 1773, north latitude 65". Thc- 
Jicat of the air was 66^,— of the water at the fur- 
^ce 5^,— of water from the depth of 68j fathoms 

^ It appears from all thefe experiments that, when 
the atmofphere was ^hotter than the furface of the 
(ea, the fuperHcial water was hotter than that at a 
great depth ; and when the atmofphere was colder 
than the furface of the fea, it is evident that the fu- 
f)erficial water was Jbmewhat coldier than that at a 
confiderable diftance below it: and I doubt not 
that this will generally be the cafe, though fudden 
charges in the temperature of the 'atmofphere, 
which cannot be in(t:andy communicated to the fea, 
may occafion particular exceptions. 

* In the year i779> f^^^^^l experiments were 
^nade^ with great accuracy,^ in order to inveftigate 
the temperature of the lake of Geneva, and of other 
Jakes in Switzerland, at different depths ; we learn 
from them, that in winter time there is very little 

# Voyage towards the North Pole, p. 143. 


538 Modes of rendering [DootVH 

difference between the heat o^the water at thefiir- 
face^ and at a great depth below it | but that bi 
fummeri the fuperficial water is confidenfab 
warmer than that which is at a great diftuo<x fion 
the furface. The experiments were made with \ 
thermometer graduated after Reaumur's ibaki 
feme of them, reduced to Fahrenheit's icale, arc 
expreffcd below. 

' Temperature of the lake of Geneva* at dificrai 
depths, in the beginning of February 1779, S^^ 
month's uninterrupted froft. 

* Heat of the open air variable froni jj 10 40 

* Water at the furface of the lake 424. 

Depth 100 feet - - 40}. 

Depth a50 feet - - ,j^^^ 

Depth 950 feet bottom 41ft 

* In another part of the lake, open air from 37 
to 40. 

Surface - - -i - ^a-V 
Depth 350 feet - • 42^ 

Depth 620 feet, bottom - 4ifJ. 

* Temperature of the lake of Neuchatel, July 

I7> 177?- 

Air .... 751 

Surface - - - - 734. 
Depth 225 feet, bottom - 41V 

Sea water may be rendered frefti by freezing, 
which excludes or precipitates the faline particles, 
or by diflillation, which leaves the fait in a mafsar 

♦ Wfttfon's Chemical Eflays, vol. ii. p. t%^. 
a . the 

Chap. 4.] Salt Water Jrefb. 539 

the bottom of the vcffel. Upon thefe principles, 

a mode of obtaining a fupply of frefh water at fea 

^vras recommended fomc years ago to the Admiralty, 

"by Dr. Irving, It confided in only adapting .a tin 

tube of fuitable dimenfions to the lid of the common 

ihip's kettle, and condenfmg the fteam in a hogf* 

bead which fcrved as a receiver. ' By this mode a 

fupply of twenty-five gallons of frefii water per hour 

might be obtained from the kettle of one of our 

fliips of war. I have not uaderftood, however, 

that the plan has been as yet introduced into general* 



[540 ] [BookVIL 

Chap. V. 


JtteapinJiftiou tfD^rina relative toj^nfmmmu E^^^orgiimu^ 
Fapo^ fy fim* fuppeftd to confifi ofbtUhnjo Fefici^s. — RaiM,^ 
Different TbeoriiJ of Raift.^-^SnO'TAj.'^^HaiL^'RaiM *afbuhfnu 
iu coming in contad nvith the Earth.^^^Large Hail-Jimm* 
Fogs,^^De'vo,^^Hoar-frifi.''^lnfiances of partial Jrnxiag^iai 
tbi general Temferaturi # j above the freezing FeinK 

IN a preceding volume, when trcaring of die 
cfFcfts of heat or fire, and particularly of va- 
pour> it was neccffary tp introduce a few obferva- 
tions relative to fpontaneous evaporation. It is 
proper, however, to repeat, in this place, that phi- 
lofophcrs are by no means agreed with rclpcft \o 
the caufe of this phenomenqp. By fbme it has 
been attributed to a folution of water in air fimiJar 
to that of faline fubflances in waters by others, to 
the afbion of the eleflric fluid. The firft of thefc 
opinions had till lately obtained almoft univerfal 
aflfent, but is now rplinquiilied, fince it is found 
that evaporadon proceeds, as well in the exhauftcd 
receiver of the air punip> as when air \t prefcnt. 
Eleftricity has been found to promote evaporation, 
and clouds are almoft univerfally ele6trical; but 
evaporation is carried on condnually where there is 
no reafon to fuppofe the [prefence of the cledfaic 
fluid, at leaft where its operation cannot be dilco- 
vered by any known teft. It is at prefent com- 

Chap« 5*] y^^f^^ompofedofbQlhwVeftcUs. 541 

monly fuppofcd, that redundant heat is the general 
caufe of the evaporation of water, and that it al* 
•ways proceeds in proportion to its temperature, 
compared with that of the furroundiilg medium. 

There is one circumftance very much in favour 
of the opinion^ that the emiflion of heat is the chief 
caufe of evaporation, which is, that every liquor 
cools when it evaporates, becaufe the portion of the 
fluid which difappears carries away a quantity of 
caloric from the liquor, which becomes latent in the 
vapour. . 

A doubt has arifen among philo&phers, whe« 
ther water, as it exifts m a tranfparent flat'e 
in the atmolphere, is in particles of an uniform 
denfity, or afTumes the form of hollow veficlcSy 
When there is a tendency to rain or fnow, it 
is known to exid in the ftate of minute drops 
and icicles; but the folutipn is then not per- 
feft, its tranfparency is impaired, and clouds are 

The exiflence of hollow fpheres is laid to have 
been actually obferved by feveral pcrfons; but as a 
microfcope of confiderable magnifying power mufl 
be employed, this may have been a fource of error, 
and may have produced delulive appearances. The 
fimpleft and moil inftruftive manner of obferving 
them is to expofe a cup of forae warm aqueous 
fluid, of a dark colour, as coffee, or water mixefd 
with ink, to the rays of the fun in a fine day, when 
the air is very calm j a cloud will rife from the 
fluid to a certain height, and then difappear. An 
attentive eye will foon difcover that this cloud con- 
fills of fmall round grains, of a whitifh colour, and 


i^i Vapaur cof0s of [Bo^k FIL 

detached one from the other. To acquire a moir 
diftinft idea of their form, they may be cbfcrverf, 
as they rife from the furfacc of the liquor, with ^ 
lens of about one inch and an half focus, bdcg 
careful, however, to keep the lens out of the va- 
pours, that they may not deprive it of tranipo* 

Spherical balls ofdifferentfizes may in this man- 
ner be obferved proceeding from the (urfacc wxtfe 
more or Icfs rapidity. The more delicate lifc 
fwiftly, and foon traverfc the field of the lens i jSbt 
larger fall back into the cup, and, without mixing 
with the fluid, roll upon its fur&ce like a ligbc 
powder, which obeys every impulfc of the air. 
The lightnefs of thefe fmall fpheres, their white- 
ncfe, &c. give them an appearance altogether diffe- 
rent from folid globulesj their perfect refemhlance 
to the larger balls, that are feen floating on the fur* 
fece of the liquid, can leave no doubt of their 
nature; it is fu/Ecient tp fee Acm to be convinced 
that they are hollow bubbles, like thofe bk>wn 
from water and foap. M. Kratzenftein endea- 
voured to eftimate their fize, by comparing them 
with a hair, and found that they were twelve times 
fmaller than the hair, the diameter of which was the 
three hundredth part of an inch, and confequcndy 
one of thefe was only the three thoufand fix 
hundredth part of the fame meafure. 

Thefe bubbles may even be fometimcS) it is iaidj 
obferved in a fog, or in a cloudy when the obfcr- 
ver is fituated on a hilL To this end M. de Saufluie 
ufed a lens of one and an half or two inches focus, 


^which he held near his eye with x)ne hand, in the 

other he held any fmooth, flat, and pollflicd furface^ 

of a black colour, as * the bottom of a tortoife 

Ihcll box, bringing this towards the lens till it was 

very near the focal diftancei he then waited till the 

agitation of the air brought fome particles of the 

cloud into the. focus of the lens; when the cloud 

was thick this foon happened, and he perceived 

round and white particles, fome pafUng with the 

rapidity of lightning, others moving flowly ; fome 

rolling on the furface^ of the tortoife (hell, others 

ftriking againft it obliquely, and rebounding like a 

ball from a wall, and others fixing themfclves to it. 

Small drops of water might alfo be feen to fctdc 

on the tortoife Ihell, but they were eafily diftin- 

guifhed from the hollow fpherules, by their tranf- 

parency, their gravity, and their pace. Further, 

clouds do not form a rainbow ; it is produced by 

folid drops; when a cloud is not in an aftual ftate of 

refolution, it does npt change the form of the ftars 

which are feen through itj for infinitely thin menif- 

cufles do not fenfibly change the courfe of the rays 

of light i but as foon as the cloud begins to refolve 

itfelf into folid drops, or even without clouds, 

when folid drops begin to be formed in the air, the 

ftars feen through them are all defined, lur* 

rounded with a diffufe light, circles, and halos ; 

hence, thefe meteors are the forerunners of rain, 

for rain is nothing more than thefe drops augmented 

or united. When the vcficular vapours arc con- 

dcnfcd by cold, the water which formed the bubble 


544 J^* ^itoiC^ rtwy fif Rain. [Book VII. 

cryftallizes^ ibmctimcs into hoar frofl:^ ibmctinics 
into fnow ; when it does not freezcj they unite in 
dewy or delcend in rain. Many other curioiB 
propefties concerning the vclicular and coociete 
vapours are related in M- de SaufTure's £(Iiu fur P 

The precipitation of water from the atmo'pheie, 
in rain has given rife to as much {peculation as 
evaporation; and it muft be confc0ed> chat the caufe 
of neither has yet been very cleaSrly afcertained 
By fome U is fuppofcd, that the capacity of the air 
(at fufpending aqueous vapour is in proportion to 
its heat> and therefore that any circumftance which 
cools the atmofphere will produce rain. If^ thert- 
fere> according to this theory, a ftratum of cold air 
meets with a warmer ftratumj a fall of rain is occa- 
fiohed» becaufe the warmer ftratufn is cooled. To 
this it has been replied, that by this mixture the 
colder ftratum muft be as much warmed as the 
warmer is cooled, and, therefor^, thatnoprecipitatkm 
ought to take place. In order to obviate diis dif- 
ficulty, Dr. Button fuppofes that heat enables the 
atmofphere to fufpend watei- in an increafing ratio, 
according to the quantity of it. Thus, if two 
degrees of heat enable a certain quantity of air to 
fufpend two given meafures of water, three d^rees 
of heat will enable the fame quandty of air to fuf- 
pend more than three fuch meafures- Upon this 
fuppofidon, if two ftrata of air, each of which is 

• Sec Adamses Leisures on Natural Philofcpby. 


Chap. 5.] "Theory ofEU&rical Pbilofophers. 545 

charged with as moch water as itd temperatufe 
enables it to fulpcnd, meet together, and are re- 
duced to a mean temperature; they will not be 
able to fulpend as much water as in then- feparate 
ftate, and a precipitation of par/t of the water will 
confequently be produced *. 

Others confider rain ai an efcftrical phenome- 
non*, and it is very, generally allowed, that elec- 
tricity at Icaft concurs with other caufcs in pro- 
ducing it. Bodies charged with the fame eleftri- 
city, whether it is negative or pofitive, always repel 
each other, and the aqueous particles Which com- 
pofe clouds, being afted on in this way, will be pre*;* 
vented from uniung into drops fufficicridy large to 
fell to the earth. The rapidity with which rain 
falls after a difcharge of lightning from a cloud, 
tends much to confirm this opinion. Rain alfo 
fells heavieft from the center of a cloud, where the 
clcdtric matter has been found by experiment to be 
generally in equilibrio; while very little is dif- 
charged from the edges, which are ufually found to 
be eleftrified either pofitively or negatively. 

The wind has been fuppofcd to have an effeft in 
producing rain, by driving the aqueous' pardcles 
into contaft, and thus caufing them to unite into 
drops. But, by experience, wind feems to have 

* That heat has a coniiderabje inflaence in rafpendiiif 
aqueous vapour, appears from the phenomenon of dew; 
which, the reader will remember, is part of the water taken 
up by the air during the day time, but which is again depO* 
£ted during the coolnefs of the night. 

t See Book IV. chap, 6. 

Vol. II. . Nn the 

546 Snow. [Book VIT. 

the direft contrary influence> and frequently pre- 
vents rain. 

Belides Tain, many other, phenonnena are pro- 
duced by the capacity which air has in differeoc 
circumftances of taking^up, fufpending, and dc^po- 
fitbg water; the chief of thefe are fnow, hai], 
(ogSy clouds, dew, and hoar froft. 

The cold of the higher regions of the atroo- 
fphere is Ibmetimes fo great, as to freeze the aque- 
ous particles which form clouds. If the particles 
beconie frozen before they have had tinne to unite 
into drops, many of the fmall icicles which are 
produced, uniting together, and being coime&ed 
only at a few points, form flocculent mafles, which 
arc called fnow. The order and arrangemenr of 
the icicles is not always the fame^ they vary greatly, 
and this produces the variety which is obfervcd 
in fnow. It is remarkable, that though fnow varies 
at different times, yet what falls together is always 
the fame ; that is, the fnow which falls at a parti- 
cular time, confifts of flakes, which vary only in 
fize, but are all formed of particles difpofed in a 
fimilar manner. We are not fufficiently acquainted 
with the laws by which the concretion or cryftalli- 
xation of bodies are regulated, to explain the caufe 
of thefe phenomena. On account of the fmall 
quantity of matter contained in fnow, in proportion 
to the furfaces expoled, it meets with great rcfift* 
ance in pafling through the atmofphere, and conic- 
quendy falls very flowly. Its great furface alfo 
renders It very fufceptible of evaporation, which 


Chap. J*] Hail 547. 

conGderably diminifhcs its weight even in the 
coldefl: weather. 

If the cold is fo moderate^ aa to allow the parti- 
cles of water to unite intp drops before congelation 
takes place, particles of ice are produced, which 
are called hail. The feme thing may be fuppofcd 
to happen when the lower regions of the atmo/phcre 
are colder than the upper, which, though contrary to 
the general courfe of things, fometimes happens, la 
fuch a cafe, the aqueous particles, after having united 
above into rain, are cong^led in their defcent, and 
are converted into hail. In the year 1775 or 1776, 
rain fell at Liverpool^ which became foUd as foon as 
it reached the furface of the earth, in fuch a man- 
ner as to give a covering of ice to whatever wa* 
wet with it, and even to form icicles on the dreft 
of perfons expofed to it. This phenomenon I have 
alfo witneffed elfewhere. 

Hail, when firft formed, muft be perfeftly round, 
becaufe formed from a fluid; and all fluids, when 
placed in fuch fituations as to receive an equal 
preflure in every direftion from the medium which 
furrounds them, naturally afliime a fpherical fomi* 
Hail, however, when it arrives at the earth is often 
angular^ this muft be explained, either by fuppo- 
£ng that the particles have begun to difiblve, or 
that they were fufficiently cold to congeal and at- 
. tach to their furface, the aqueous particles with 
which ^ey came into contad in their fall. Hail, 
when firft formed,, is never larger than the drops of 
water which fall in rain; but from the caufc juft 
.fDcntioned^ hul-ftones have fometimes been known 
N n 3 ^ ^ W 

^4» ^^ CBookvn, 

to &11 as. large as nuts^ or even as hens' eggs. lo 
order to convince ourfelves, that iuch hail-ftooes 
owe their extraordinuy fize to the additions whicb 
they receive in falling, it is only necefikry to eza 
mine them: they will aknoft uniformly be Cbuod 
to be angular^ and never to have an uniferm denlky 
from the circumference to the center^ which clearly 
proves, that they are compofed qf difierent para- 
des of ice conne£l^d together* In confirmation of 
the fameopinion> it is obferved> that the hail whidt 
&lls on mountains^ is fmaller than that which 
4efcends in the neighbouring vaUies. The iainc 
obfervation has been repeatedly made with rrfpeft 
to rain, by perlbns in the habit of afcendbig 
mountaiBS, for the purpofe of philofophical expeii- 

It fometimes happens &om the fbce of the atmo- 
fphere, or a concurrence of circumftances not 
eafily to be afcertained, that a great quantity of 
aqueous parades are raifed in the atmoiphcre» 
where, being incompletely diflblvedj they form a 
thick vapour, which extends itfelf in the lower part 
of the atmofphere ^ thefe particles, deftroyxng the 
traniparency of the atmo^here, form fogs. Fogs 
are more frequent in low^ wet, and marfhy fitua- 
tions, near rivers and ponds, than in fuch parts of a 
country as are elevated and dry. It (bmetimcs 
happens, that certain exhalations are mixed with 
fogs, which are perceived by their unpleaiantfinell^ 
and by an acute fenfation which is felt by the throat 
and eyes. 

Fogs are piuch more frequent in cold feaibns>« 
5 and 

Chap. 5.] Fogs. SA9 

and in cold climateSj than in fuch as are warni> 
becaufe in the former^ the aqueous particks being 
condenfed almoft as foon as they proceed from the 
furfece of the earth, arc incapable of rifing into the 
higher parts of the atmofphero. If the cold is 
augmented, the fog freezes and attaches itfelf in 
fmall icacles to the branches of trees, to the hair 
and clothes of perfons expofed to it, to the blades 
of graft, &c. 

When fogs rife to a confiderable^ height in the 
atmolphere, and are collefted in a denfe ftate, 
whether this happens from any a6tionof the air or 
from, othdr caufes, they form clouds, which float ia 
different regions of the atmofphere according to 
their fpecific gravity; fince they neceflarily rife 
or fall, till they arrive at that part of the atmo- 
Iphere which is in equilibrium with chemfelves* 
As the atmolpherc is heavieft below^ denfe and 
thick clouds, which are at the point of uniting into 
rain, float near the furface of the earth, while the 
fleecy and thin clouds foar aloft. We often obferve 
both kinds at different heights in the atmofphere at 
the fame time. As clouds are formed of water^ 
they arc mofl copioufly produced where the air has 
mofl opportunity of afting on that fluid. Confe- 
quently winds which blow from the wefl and fbuth** 
wefl:, from the adantic ocean, bring more clouds 
to this country than eaflerly winds, which only pals 
over a narrow channel of the fea. 

During the day time the fun heats the earth, 

water, air, and every thing which is expofed to its 

rays. The heat communicated to all thefe bodies 

is diminifhed afcer fun fet, but the air is more fud- 

N n 3 dcnly 

5JO t)fw. [BcokVIL 

dcnly cooled than the more folid bodies. Heatf 
therefore, which has always a difpofition co dif- 
tribute itfelf equally, pafTes from the furface of 
Vater and earth into the air, and carries with 
it fome aqueous particles, which are fufpcndcd 
near the furface. When the cold increafes during 
the night, thefe vapours are condenfcd, and occa- 
iion that dampnefs which is felt on the clothes of 
perfons cxpofed to the night air, and form that dew 
which is fo refrcfliing to vegetables fcorched during 
the day time by the fummcr's fun. 

In cold weather the dew becomes frozen into 
hoar froft, for the formation of which it is notne- 
ceffary ohat the earth, or even the air,lhould be ib far 
cooled as to occafion the congelation of water into 
ice. This fadt can only be explained, by confidcr- 
ing that thefe fmall drops of water ?xpofe a large 
furface to the aftion of the air ; and by this cneaiis 
evaporation, which powerfully produces cold, is 
promoted. For the fame reafon clothes hung out 
to dry, are frequently frozen ftid*, when no ice k 
formed in water expofed to the fame degree of cole}, 
but in circumftances lefs favourable to evaporatioiu 


Chap. 6.] C 55J ] 

Chap., VI. 


Origin of Springt.— 'Digging of WtHt.'—Itaturt rf Springs.-^ 
Marjhes. — Cheap and tafy Modi of drtaning thtm.-^Iwttrmit'' 
ting Springs.— Rivtrt.—Ti*ifS«uree, Ht. 

T HE water whichfalls onthefurfacc of the earth, 
in rain, fnow, &c. penetrates its fubftance 
till it meets with a ftratum of clay^ ftone, or fome 
ocher matter which flops its defcent ; it then glides 
laterally on the ftratum which fuftains it, and in the 
direftion to which it leans, till meeting with an aper- 
ture, it appears on the fur&ce of the earth in the 
form of a fpring. As water always has a tendency 
to defcend, fprings are always lower than the iburce 
from which they are fujpplied ; iprings are moft 
common, on the fides and at the bottom of moun- 
tains i they are feldom found quite at the fummit of 
a mountain, and are rare where a country is every 
where level to a confiderable diftance, becaufe there 
theftrata are parallel, and do not conduct the water 
to any particular point. In order to obtain water, ' 
therefore, in flat countries, it is in general neceflary 
to dig into the earth, when it is found to flow co« 
pioufly from the fides of the opening, at no great 
diftance from the furface. When wells are dug in 
elevated fituations, water is feldom met with till 
we have dug to a confiderable depth, and got below 
the general level of the country, 

N n 4 A curious 

55a tHsgingof mUs.. [BookVIL 

A curious circumftance occurs in the making of 
wells at Modena and Stiria in Italy. The workmen 
begin by digging through fcvcral ftrata or foils, till 
they come to a very hard kind of earth much re- 
fcmbling chalk ; here they begin their mafon-work» 
and build a well, which they carry on at their leifure 
till they have finifhed it, without being interrupted 
with one drop of water, and without any appre- 
henfipn of not finding it when they come to 
make the experiment. The well being finifhcd» 
they bore through the hard bed of chalk, upon 
which the well is built, with a long auger, but take 
care to get out of the wcU before they draw it out 
again ; which when they have done, the water (prings 
up into the well, and in a little time rifes to the 
brim, nay fometimes overflows the neighbouring 
grounds. Now there can be little doubt, that thefe 
waters flow from refcrvoirs which are coUefted 
within the Appennine mountains, not far from 
Modena, and taking their courfe through fubter* 
raneous paflages, endeavour to force their afcent 
to the fame height from which they delcend, where- 
ever they can find a vent. 

As all the water which falls in rain has under- 
gone a natural diftillation, it is much more pure 
when it firft falls, than after it has paflfed through 
^iflfcrent ftrata of the earth and riles in fprings. 
Spring water is always found to contain fome foreign 
admi5cture; if this ihould be only an earthy fak, the 
water is Called hardi if it contains other fubftances, 
it then receives the denomination of mineral water; 


Chap. 6.'] Cheap Mode of drainmg Marjb Lands. 5 53 

but thefe will require to be treated of in a diftinfk 

The water which lies upon marlhes and fwampy 
grounds, has generally its fource in feme fpring^ 
which is placed above the level of the marih. The 
foil, therefore, in thofc places, being generally of n 
fpongy texture imbibes the water, and permits it to 
difperfe through its whole mafs, rather than force 
its way through a certain aperture s and as mar(h* 
lands are commonly level, the water will be more 
eafily difFufed through the foil, than it can be upon 
the declivity of a hill. The great art, therefore, in the 
draining of marlhes is to difcover the fource, which 
may be looked for on the brow of fome eminence 
which overhangs them ; and it may generally be 
jibund by obferving where the boggy part grows 
narrow and angular, and points as to an apex> 
which is the fpring whence all the mifchief pro- 
ceeds. When the fource is once difcovcred, the 
water may be eafily drawn off by drains, aquedufts, 
or pipes, according to the circumftances of the 
cafe. The common mode of draining land by 
cutting deep trenches, or drains, through the 
marfh itfelf, to ferve as refervoirs for the watery 
is much more laborious and expcnfivc, and indeed 
fcldom anfwers the end propofed ; for as foon as 
the trenches fill, the ground is rendered as fwampy 
as ever; and even where drains are made on die 
principle of an inclined plain to draw off the water, 
they are frequendy Hopped by the mud of the 
marfh, and the leafi: ftoppage expofes the land again 
to at leaft a partial overflow. 


554 Iniermitiing [Book VII, 

There are fomc iprings which exhibit a vciy co* 
rious phenomenon, a kind of tide or intermifllocy 
by which the water at certain periods appears to rife 
to a confiderable height, and gradually to fubfide. 
Thefe are called intermitting fprings. It was loi^ 
imagined, that thefe fountains were repIeniOied by 
Ibme connefbion with the fea ; that the water was 
frefhened by its progrefs through fand and earth, and 
that their riling and falling depended on the tide. 
Jt was, however, found, that the periods of the water 
ri(ing and falling in thefe fprings, did not correffX}od 
in point of time with the tides of the adjacent feas, 
and that the periods were different in different 
fprings, contrary to the regular rifmg and falling 
of tides in the ocean. The phenomenon has (ince 
been very fatisfaftorily explained, and upon a very 
Ample and obvious principle. Ic has been al- 
ready ihewn, that when a fiphon is inferted in a 
veffcl contsuning water, if the air is drawn out of 
tlic fiphon, or by any means the water is n^ade to 
flow over the bene of the tube, which lies above 
the brim of the veffcl, the water will continue to 
flow over the brim through the fiphon till the whole 
IS cxhaufted. 

To account, therefore, for the intermitting ipring, 
we have only to fuppofe, that a cavity or receptacle 
is formed in the bowels of the hill or mountain, 
where the fpring is ficuated, which gradually fills 
with water like other rcfcrvoirs ; by the bterpofi- 
tion of fome ftratum of ftone or rpck, the tube or 
cavity which conveys the water from this receptacle 
to the ipring or mouth where it iffucs^ isbenc 




Fuf, 2. 


P^- 3 

Fi0. 4. 

Chap. 6.] Springs. 555 

in the form of a fiphon, the bent of which is con- 
fiderably higher than the bottom of the rcfervoir. 
'Whenever, therefore, the rcfervoir or receptacle is 
filled as high as the bent of the tube, the .water will 
rife in it to its level, and begin to flow into the fpring, 
which will continue till the receptacle is cxhaufted 
While this procefs is going on the water in the fpring 
will rife ; and as foon as the receptacle is exhauft- 
cd, the water, being drawn off by a ftream or rivu- 
let, will appear to fall in the well of the fpring, and 
will continue to fall till the receptacle is again fup- 
plied to the height of the fiphon or tube, when the 
procefs of filling will be again renewed. 

To render the matter perfectly plain, let A B C 
(Plate X. Fig. 4.) reprefent the cavity or recep- 
tacle, from the bottom of which C proceeds the 
tube or fiphon D E. When the water rifes in the 
receptacle to the level of E in the tube, it will begin 
to flow into the fpring at D, on the principle ex- 
plained in the preceding paragraph, and the whole 
phenomenon will be eafily accounted for. 

With any perfon who has carefully obferved the 
courfc of rivers, and traced them to their fources, 
there can be litde doubt that they are formed by 
the confluence of fprings, or of the litde ftreams or 
rivulets that iflu'e from them ; with perhaps the 
exception of thofe rivers which proceed from lakes, 
where the rcfervoir is ready formed, and generally 
by the fame means. 

In the beginning of the prefent century, the phi- 
lofophical world was agitated by a debate con- 
cerning the origin of thofe waters which arc neccf- 


556 Contrsverfy cmcerning [Book Vfl, 

fary for the fupply of rivers, &c. one party contend- 
ed ftrongly for the exiftccice of a large' mais of water 
within the bowels of the earth, which fupplied not 
only the rivers but the ocean itfelf j at the head of 
thefe we may place the ingenious but fanciful 
Burnet. The French philofophcrs, on the contrary, 
aflerted, that the waters of the ocean were convey- 
ed back by ibme fubterraneous parages to the 
landj and being filtrated in their paflage, returned 
again to the fea in the courfe of the rivers ; but ths 
opinion appears contrary to all the known prin- 
ciples of hydroftatics. 

In oppofition to thefe hypothefes, our illuftrious 
countryman Halley contended that the procefs of 
evaporation, and the immenfe dcpofition of water 
in confequence of it, was fully adequate to the 
whole fupply. If) indeed, we confider the im- 
menfe quantity of water which is continually car- 
ried up into the atmofphere by evaporation, as 
ftated in a former chapter, and confider that this is 
a procefs which is continually going on, not only 
from the ocean but from the rivers themlclves, and 
from the whole furface of the earth, we fliall ftc 
but litde tcafon to doubt of Dr. Halley 's hypothcfis, 
but may rcafonably conclude, that this kind of cir- 
culation is carried on through all nature, and that 
the fea receives back again through the channel of 
the rivers, that water which it parts with to the at- 

* All rivers have their fource either in mountains, 
or elevated kjces; and it is in their defcent from thefc, 
that they acquire that velocity which maintains their 


Chap. 6.1 the Supply of Rivers, 6?r. 557 

future current. At firft their courfc is generally 
rapid and headlong j but it is retarded in its journey 
by the continual friftion againft its banks, by the 
many obftacles it meets to divert its ftream, and by 
the plains generally becoming more level as it ap- 
proaches towards the fea. 

* Rivers, as every body has ktn, are always 
broadeft at the mouth 3 and grow narrower to- 
wards their fource. But what is lefs known, and 
probably more deferving curiofity, is, that they run 
in a more direft channel as they immediately leave 
their fources ; and that their finuofities and turn^ 
ings become more numerous as they proceed. It 
is a certain fign among the favagcs of North Ame- 
rica, that they are near the fea, when they find the 
rivers winding, and every now and then changing 
their direction. And this is even now become an 
indication to the Europeans themfelves, in their 
journies through thofe tracklefs forefts. As thofe 
finuofities, therefore, increafe as the river ap- 
proaches the fea, it is not to be wondered at, that 
they fometimes divide, and thus difembogue by 
different channels. The Danube difembogues into 
the Euxine by feven mouths -, the Nile, by the fame 
number ; and the Wolga, by feventy. 

* The largefl: rivers of Europe are, firfti the 
Wolga, which is about fix hundred and fifty leagues 
in length, extending from Refchow to Afbachan. 
Ic is remarkable of this river, that it abounds with 
water during the fummer months of May and June ; 
but all the reft of the year is fo fhallow as fcarce to 
coverits bottom^ or alloiy a palTage for loaded vef-. 


55* Rivers of [Book?IL 

ftls that trade up its ftfcam. The next in order is 
the Danube. The courfe of this is about four hun* 
dred and fifty leagues^ from the mountains of Swi:- 
ztrland to the Black Sea. The Don, or Tanais, 
which is four hundred leagues fi-om the (burcc of 
that branch of it called the Softna, to its mouth 
in the Euxine Sea. In one part of its courfe it 
approaches near the Wolga ; and Peter the Grear 
had aftually begun a canal, by which he intended 
joining thofc two rivers ; but this he did not live 
to finilh. TheNieper, or Boryfthenes, which rifts 
in the middle of Mufcovy, and runs the courfe of 
three hundred and fifty leagues, to empty icfcif into 
the Black Sea. The Old Coflacks inhabit the banks 
and iflands of this river ; and frequently crofs the 
Black Sea, to plunder the maritime places on the 
coafts of Turkey. The Dwina, which takes its 
rife in a province of the fame name in Ruflia, 
that runs a courfe of three hundred leagues, and 
difembogues into the White Sea, a little below 

« The largeft rivefs of Afia are, the Hohanho, in 
China, which is eight hundred and fifty leagues in 
length, computed from its fource at Raja Ribron, 
to its mouth in the Gulph of Changi. The Jenifca 
of Tartary, about eight hundred leagues in length, 
from the Lake Selinga to the Icy Sea. This river 
is, by fome, fuppofed to fupply moft of that great 
quantity of drift wood which is feen floating in the 
fcas, near the Artie circle. The Oby, of five hun- 
dred leagues, running from the lake of Kila into 
the Northern Sc4, The Amour, in Eaftern Tar- 

Chap. 6*] Eurtfpe and Afia. 559 

tary, whofc courfc is about five hundred andfevcn* 
ty-five leagues, from its fource to Its entrance into 
the fta of Kamtfchatka. The Kiam, in China, five 
hundred and fifty leagues in length. The Ganges, 
one of the mofl noted rivers in the world, and about 
as long as the former. It rifes in the mountains 
ivhich feparate India fromTartary; and running 
through the dominions of the Great Mogul, dif- 
charges itfclf by feveral mouths into the bay of 
Bengal. It is not only efteemed by the Indians for 
the depth, and purenefs of its ftream, but for a fup- 
pofed ianftity which they believe to be in its wa- 
ters. It is vifited annually by feveral hundred thou- 
fand pilgrims, who pay their devotions to the river 
as^to a god s for favage fimplicity is always known 
to miftake the bleffings of the deity for the deity 
himielf. They carry their dying friends, from 
diftant countries, to expire on its banks ; and to be 
buried in its ftream. The water is loweft in April 
or May ; but the rains beginning to fall foon after^ 
the flat country is overflowed for feveral miles, till 
about the end of September; the waters then begin 
to retire, leaving a prolific fediment behbd, that 
enriches the foil, and, in a few days time, gives a 
luxuriance to vegetation, beyond what can be con« 
ccved by an European. Next to this may be reck* 
oned the ftill more celebrated river Euphrates* 
This rifes from two fources, northward of the city 
Erzerum, in Turcunriania j and unites about three 
days journey below the fame, whenct, after per- 
forming a courfe of five hundred leagues, it falls 


560 Rivers of j^rka. £Book VU 

into the Gulph of Perfia, fifcf miles below the axj 
of Baflbra in Arabia. The river Indus is extend- 
cd» from its iburce to its difcharge into the Aratec 
fea, four hundred leagues. 

* The largcft rivers of Africa are, the Senega^ 
which runs a courfe of not lefs than eleven hun- 
dred leagues, comprehending the Niger, which 
fome have fuppofcd to fell into it. However, 
later accounts fccm to affirm that the Niger is fcft 
in the fands, about three hundred miles up fiom 
the wefterrt coafts of Africa, Be this as it may, 
the Senegal is well known to be navigable for more 
than three hundred leagues up the country ; and 
how muth higher it may reach is not yet difcover- 
ed, as the dreadful fatality of the inland parts of 
Africa, not only deter curioficy, but even avarice, 
which is a much ftronger paffion. The celebrated 
river*Nile is faid • to be nine hundred and Icvency 
kagues, from its fource among the mountains of 
the Moo», in Uppbr ^Ethiopia, to its. opening into 
the Mediterranean Sea. Upon its arrival in the 
kingdom of Upper -^gypt, it runs through a 
rocky channel, which fome late travellers have 
miftaken for its catarad:s. In the beginning of ics 
courfe, it receives many leffer rivers into it; and 
Pliny was miftaken, in faying that it received none. 
In the beginning alfo of its courfe> it has many wind- 
ings; but, for above three hundred leagues from the 
fea, runs in a dire£t line. Its annual overflowings 
arife from a very obvious caufe, which is almoft 
univerfal with the great rivers that take their fource 


Chap. 6.) Ot)erPomi9gs tfihe Nik. 56 1 

near the line. The rainy feafon, which is periodic 
cal in thofe climates, floods the rivers; and as this al- 
ways happens in our fummer, fo the Nile is at that 
time overflown. From thcfe inundations, the in- 
habitants of Egypt derive happmefs and plenty ; 
and, when the river does not arrive to its accuftom- 
ed heights, they prepare for an indifferent harveft* 
It begins to overflow about the 17th of June 1 
it generally continues to augment for forty days, 
.and decreafes in about as many more. The time 
of increafe and decrcafe, however, is much more 
inconfiderable now than it was among the ancients. 
Herodotus informs us, that it was an hundred days 
riflng, and as many falling ; which ihews that the 
inundation was much greater at that dme than at 
prefent. M. BuflTon * has afcribed the prcfcnt di- 
minution, as well to the leflening of the mountains of 
the Moon, by their flibftance having fo long been 
walhcd down wich the ftream, as to the riling of the 
earth in £:;ypt> that has for io many ages received 
this extraneous fupply. . But we do not find, by the 
' buildings that have remained fince the times of the 
ancients, that' the earth is much raifed fince then. 
Befides the Nile in Africa, we may xeckon the 
Zara, and the Coanza, from the greatnefs of whole 
openings into the lea, and the rapidity of whofe 
ftrcamsj w^ form an eftimate of the great diftance 
whence they come. Their courfes, however, are 
fpent in watering deferts and favage countries, whofe 
poverty or fiercencfs have kept ftrangers away* 

* BaffMi, vol. ii. p. Si. 

Vol. II. - O o * But 

S6i ^fmericM [BookViL 

^ But of all parts of the world, America, as it 
exhibits the moil lofty mountains, fo alfo it iupplies 
the largcft rivers^ The principal of thcfe is the 
great river Amazons, which, from it& (burce in the 
lake of Lauricocha,to its difcharge into the Weftcm 
-Ocean, performs a courfe of more than twelve 
hundred leagues *. The breadth and depth of this 
: river is anfwerable to its vaft length; and, where 
its width is moft contracted, its depth is augmented 
in proportion. So great is the body of its waters, 
that other rivers, though before the objeits of ad- 
miration, are loft in its bofom. It proceeds after 
their junftion, with its ufual appearance, without 
any vifible change in its breadth or rapidity ; and, 
if we may fo exprefs it, remains great without often* 
tation. In fome places it difplays its whole muni- 
ficence, dividing into feveral large branches, and 
cncompaffing a mulcitude of iflands; and, at length, 
■difcharging itfclf into the ocean, by a channel of 
an hundred and fifty miles broad. Another river, 
that may almoft rival the former, is the St. Law- 
rence, in Canada, which rifing in the lake Afilni- 
boils, pafles from one lake to another, from 
Chriftinaux to Alempigo; and thence to lake 
Superior j thence to the lake Hurons ; to lake 
Erie ; to lake Ontario j and, at laft, after a courfe 
of nine hundred leagues, pours their collected wa- 
ters into the Atlantic ocean. The river Mifliflippi 
is more than feven hundred leagues in length, 
beginning at its fource near the lake Afliniboils, 
and ending at its opening into the Gulph of Mcxi- 

» Ulloa, vol.i- p. 388. I 


Chap. 6.] Rivers. ^63, 

CO. The river Plata runs a length of more than 
eight hundred leagues from its fource in the river 
Parana^ to its mouth. The river Oroonpko is feven 
hundred aiid fifty leagues in length, from its fource* 
near Pafto, to its difchargc into the Atlantic ocean. 
* Such is the amazing length of the pr^ateft rivers i 
and even in fomc of thefe, the moft remote fburccs 
very probably yet continue unknown. In faft, if 
we cohfider the number of rivers which they re- 
ceive, and the Jitde acquaintance we have with the 
regions through which they run, it is not to be 
wondered at that geographers are divided coiKrem- 
ing the fources of moft of them. As among a 
number of roots by which nourilhment is conveyed 
to a ftately tree, it is difficult to determine precifely 
that by which the tree is chiefly fuppliedj fo among 
iche many branches of a great river, it is equally 
difficult to tell which is the original. Hence it may . 
cafily happen, that a fimilar branch is taken for the 
capital ftream j and its runnings are purfued, and 
delineated, in prejudice of fome other branch that 
better deferved the name and the defcriprion. In 
this manner *, in Europe, the Danube is known to 
receive thirty leffer rivers j the Wolga thirty-two 
or thirty-three. In Afia, the Hohanno receives 
thirty-fivej the Jenifca above fixty; the Oby as 
many J the Amour about forty j the Nanquia 
receives thirty rivers ; the Ganges twenty ; and 
the Euphrates about eleven. In Africa, the Se- 
negal receives more than twenty rivers; the Nile 
receives not one for five hundred leagues upwards, 

• Buffon« vol. ii. p. 74. 

Oo 2 And 

5 64 Puicdicdl Inundatms. [Book VIL 

and then only twelve or .thirteen. In America, the 
river Amazons rcceivcs^abovc fixty, and thofe very 
confiderable; the river St, Lawrence about fortft 
coimdng thofe which fall into its lakes; theMifliflippi 
receives forty; and the river Plata above fifty*/ 

The inundaridns of the Ganges and the Nik 
h^ve been already mendonedj and it might be add- 
ed» that almoft all great rivers have their periodicd 
inundations from (imilar caufes. The author al- 
ready quoted obfervcs, that, ' befides thefc annua% 
periodical inundations^ there are many rivers that 
overflow at much fhorter intervals. Thus moft of 
thofe in Peru and Chili have fcarce any motion by 
night ; but upon the appearance of the morning fun 
they refume their former rapidity : this proceeds 
from the mountain fnows, which, melting with 
the heatj encreafe the dream, and continue ca 
drive on the current while the fun continues to 
diffolve them.' 

There are fome rivers which are faid to lofc 
themfelves in chafms under the earth, and to flow 
for fcvcrai miles in fccret and undifcovered chan- 
nels. On this circumftancc is founded one of the 
moft beautiful fables of antiquity, relative to the 
fountain of Arethufa, in Sicily. The fame thing is 
afiirmed'of the Rhine, and even of the river Molcj 
in Surrey, which, from this circumftancc, derives 
its name. With rcfpeft to the two latter rivers, 
however, fome doubts are entertained of the fifli 
but thcfe are rather a* fubjedt of inquiry to die 
geographer than to the natural hiftorian^ 

• Goldfmith's Eardi, p. soo. 


-Chap. 7-3 C 565 ] 

Chap. VII. 


Probahli Caufii of tbefi Pbenomtna.-^MouvJ mtft in <vokauic 
Regiws^'^Hot Springs in laland^ near Mount Hecla.'^At 
Gey/er.-^ln the IJland of Ifcbia. — At nterbo.-^Explanation of 
theft Phenomena. — Burning ff^eJi in Lancajhire, -^Explained. 

THERE arc few objefts in natural hiftory, 
which prefent themfclvcs to our coiifidera- 
tion, accompanied with greater difficulties than thofc 
tepid fprings, which exift in different parts of the 
world, of different degrees of temperature, and 
exhibiting a variety of the moft curious phenomena. 
Many of thefe have cxifted as long as the earlieft 
records, and for whole centuries have exhibited litll? 
variation in their temperature. 

If any circumftance could ferve to fupport the 
very dubious hypothefis of an immenfe refervoir 
of fire in the center of the earth, it would be ' 
thofc phenomena i ^et there is but little reafon to 
fuppcfe that the origin of thefe tepid fprings lies at 
any vaft d^th beneath the furfacc j and, indeed, if 
wc ^dmit the notion of a central fire, itseffcft ought 
to be more general than it is found to be« The moft 
probable hypothefis is, therefore, that the faine 
caufes operate to produce thefe, which produce 
volcanoes ; and the only inference to be drawn from 
their permanent temperature is, that the mafles of 
matter, which produce volcanic eruptioos, may 
O p 3 cxift 

^66 Hot Springs [Book VII. 

€xift for a long ferles of time, even in a ftatc of in- 
flammation, without burfting thofe bandages with 
which nature has confined them; and that heat may 
long be continued to a confiderable degree in the 
earth, without exhibiting to our aflrighted fenies 
the formidable phenomenon of a volcanic fire. 
• It is, however, in volcanic regions, that tepid 
waters are found in the greateft quantity ; and it is 
in thefe that they difplay the moft ftriking pheno- 
mena. At Laugervarm, a fmall lake, two days 
journey from Mount Hecla, in Iceland^ there 
are hot fpoueing fprings, one of which throws up 
a column of water to the height of twenty-four 
ieet. A piece of mutton and fome falmon trout 
^erd almoft boiled to pieces, in Gx minutes, in one 
of fhefe fprings. At Geyfer, in the fame ifland, 
there are forty or fifty fpouting fprings within the 
compafs of three miles ; in fome the water is im- 
pregnt-ted with clay, and white in its appearance; 
in fome, where it paffes through a fine ochre, it is 
red as fcarlet ; in fome it fpouts forth in a con- 
tinued ftreamj in others, at intervals, like an 
artificial jet d'eau. The largeft which Von Troil 
obfcrved had an aperture nineteen feet in diame- 
I3er, through which tlie water fpouted, at intervals, 
nine or ten times a day ; round the top of it is a 
bafon, which, together with the pipe, is in the 
form of a caldron 5 the margin of the bafon is nine 
feet higher than the conduit, and its diameter fifty- 
^x feet. The water was thrown up in an immenfe 
column, at difl^erent times, to the height of from 
lljirty tofixty feet, and at one time to the height of 
■ . - • • ninety- 

Chap. 7.] in Iceland. 51^7 . 

ninety- two feet. . Previous to this cxploGon' the 
earth began to tremble in three different places, 
and a noife was heard like a battery, of can- 
non *. 

.Another writer dates, that at Geyfer, in Iceland, 
there fprings up a hot water, which, upon cooling, 
depofits filiceous earth j and that of this very 
matter it has formed for itfelf a crater, in which 
columns of water, of a ftupendous bulk, after they 
have been thrown to the height of ninety feet and 
upwards, fall, and are again received. The heac 
of the water during the explofion cannot be mea^ 
fiired ; but after it has rifen and fallen through a 
ftratum of air ninety feet thick, it raifes the ther- 
moifieter to a 12% which evinces that the heat in 
the bowels of the earth muft be much more in- 
tenfe ; and at this we fhall ceafe to wonder when 
we confider, that in this cafe the fubterraneous fire 
a6ts upon the water in caverns, clofcd up by very 
thick ftrata of ftoncs, an apparatus far more effec- 
tive than Papin's digefter. The crater was at firft 
undoubtedly formed, and is daily ftrengthened by 
filiceous earth, which- quits the menftruum on its 
being cooled, falls down, and, being in ibmewh;at 
like a foft ftate, concretes f . 

About fixty yards from the ftiore of the ifland of 
Ifchia, at a place called St. Angelo, a column of 
boiling water bubbles on the furface of the fear 
with great force, and communicates its heat to the 

• Von Troir« I.etters on Iceland^ 
t Bergman's Diflert. 13. 

O o 4 water 

5^4 Hot Springs in Itafyy and England. [Book VIX. 

water of the fca near it. It boils winter and fum- 
mer, and is of great ufc to the inhabitants in bend- 
ing their planks for Ihip-building, &c. The filher- 
men alfo frequently employ this curious caldron 
tp boil their fifh. Near the fliorc of this iQand 
Sir William Hamilton found, when bathing in the 
^a^-many fpots where the fand was fo intcnfely hot 
under his feet as to oblige him haftily to retire. 

There is alfo a boiling fpring near Viterbo, in 
the Roman ftate, called the Bullicame. It is a 
jircular pool of about fixty feet in diameter, and 
exceedingly deep, the water of which is conftandy 
boiling. It is fituated in ^a plain furrounded by 
volcanic mountains. A ftony concretion floats on 
the furface of the pool, which, being carried off by 
the fuperfluous water, is depofited, and is con- 
(lantly forming a labes or tufa, of which the foil 
all around the pool is compofed. 

Thefe fountains are beft accounted for by fuppof- 
ing the pipe or iconduit to communicate with a 
large refcrvoir of water, which, being fubjeft to 
the heat of a volcanic fire, the fteam generated in 
the refervoir by the boiling of die water afts for- 
cibly op. !(h.e wafer in the (haft or pipe, and cjefts 
it by its elaftic force in the form of a fountain, 
which will aft with more or lels vigour accordincy 
to die degree of heat, and according to the refiftt 
^nce which the water encounters in its paffa<»e. 

The moft fingukr circumftance is the number 
of thefe fprings which are found in almoft every 
pountry i and even in thofc countries which have 
Jong ceafed to be vokanic. England idejf has its 


Chap. 7.] Burning TFeUs. ^69 

tepid fprings, and thofe of Bath, Buxtoft, &c. arc 
well known. Cambden mentions a well, near 
Wigan, in Lancafhirc, which was called the burn- 
ing well. If a candle was applidd to its furface, he 
fays, a flame was excited like that of ardent fpirits 
fet on Bre, and the heat and inflammation thus ex- 
cited wpuld continue fomctimes for the (pace of a 
-whole day, and was fufBcient to boil eggs, and even 
meat. As I recoUeA, Cambden mentions the well 
as having lofl: its inflammable property in his time; 
but he notices two others of a fimilar defcription, 
one in the fame neighbourhood, and another in 
Shropfliire. I have, never myfclf witncflcd a 
fimilar phenomenon, nor do I know of any fuch 
that exifts at prefent, at le^ft in Britain. 

Should, however, the fa6t be as it is related by 
Cambden, the reader, after what has been fl:ated in 
a preceding chapter, will not find it difficult to* 
explain the caufe. The country where the well is, 
or was (ituated, abounds in coals. The well is 
therefore impregnated with naphta, or fome bitu- 
minous vapour; this, upon the application of an 
ignited body, is capable of inflammation, and can 
even communicate a confiderable portion df heat 
to the water of the well itfelf. There is no proofi 
however, that the Bath or Buxton waters are im- 
pregnated with any bituminous matter, though 
coals are plentiful in the neighbourhood; and as 
thefe waters contain a fmall portion of iron, there 
is reafon to fuppofc them connefted with beds of 
pyrites, or pofllbly with a latent fubterraneous fire. 


J70 Tepid Springs. [Book YIL 

On the whoIe> we arc not fufficiently acquainted with 
the internal parts of the earth to account iacislaclorily 
for thefe and other phenoraiena of a (imilar kind^ and 
whatever is advanced in the way of theory on thcfc 
topics Ihould be advanced with becoming diffi- 
dence, and rather with a view of exciting the at- 
tention and curiofity of others, than for the pur- 
pofc of eftablilhing a fyftem unfanftioned by 
experiment, or building a reputation on the fallibit 
baGs of mere hypothefis. 


Chap. 8.3 [ 571 ] 

.C H A p. VJII. 

Capacfty of Water as a Solvent. ^^Suhftances commonly found in 
Mineral Water s.-^Fixtd Air. — Mineral Atids. — Alkaline Salts. 
^-^Neutral Salts. '^Earthy Suhflances, — Sulphur. — Metals."^ 
Mode of examining and analisung Mineral Waters, ^-^Cbetnical 
^eflsj'^'^nalyfis of the moft celebrated Mineral or Spa Waters, ~^ 
jiiX'la-Cbapelk. — Bath. — Briftol-^ Buxton,-^ Cheltenham.-^ 
Ep/bm.^-Harro'wgaie.^^MatlocL^^ Pyrmont.^^ Scarborough.-^ 
Spa. — RefieSions on the Ufe of Mineral Water in general. 

THE capacity which water has of holding a 
variety of fubftanccs in folution has been 
frequently mentioned in the courfc of thefe volumes, 
and indeed is a faft fo well known and underftood, 
that to infift much upon it would be ufelefs and 
even impertinent. 

It was alfo intimated, that the water of Iprings 
receives the name of mineral water from the fo- 
reign fubftances which are contained in it. Theft 
fubftances are various, and more than one is com- 
monly found in mineral waters j but in general they 
may be referred to the following heads : 

I. Fixed air, or carbonic acid gas. This ingre- . 
dient occafions an appearance of brifknefs in water, 
fimilar to that of fermenting liquors, which is chiefly 
obfervable when the water is poured from one vef- 
fel into another. It is very volatile, and foon 
efcapes on the water being expofed to the air. This 


57 2 Ingredients if £Book VIL 

ingredient frequently occafions giddinefs in peribos 
who are not accuftomed to it. An artificial water 
of this kind may be prepared at any time by im- 
pregnating water with fixed air. 

a. The vitriolic, nitrous, and muriatic acids. 
One or other of thefe acids exift in almoft all irine* 
ral waters ; they are ufually combined with earthy 
or metallic bafcs, but fometimes, elpecially the vi- 
triolic, exift in a feparate ftate, fo as to occafion a 
fcnfiblc acidity. 

3. An alkaline fait is found in many waters in 
Hungary, Tripoli, and other countries. It is 
ufually the fofliUalkali which is combined with fix- 
ed air in the Seltzer waters, and with the mineral 
acids in a great variety of others. The vegetable 
ftnd volatile alkajies rarely or never arc ingredients 

1 Ip mineral waters. 

4. Neut;ral Ales are not ynconimon in fprings. 
Common fliit, nitre, and vitriolated magnefia, ^re 
the mdft ufual -, tlie latter is very abundant in a fpring 

' at Epfom, in Surrey, and has therefore obtain- 
ed the name of Epfom fait. Sal amoniac has alfo 
been founcj in fonne fprings in the neighbourhood of 
volcanoes and burning coal mines, 

5. Earthy fubftances. Of thefe the calcareous 
IS fometimes found to abound fo much, as to be de- 
poGced on fuch fubftances as it comes in contaft 
with, and occafion petrifadtion. In this c^fe the 
fufpenfion of the calcareous earth feems to depend 

i on the prefence of fixed air, which, making its 

efcape .when the water iffues into the open air, 
fviffers the calcareous earth ^o feparate. The calca- 


Chap. 8.] ACmral fTatefS. 573 

reous earth of waters is^ very commonly united 
-^ith the vitriolic acid, and exifts in the form of 
gyplum, which H only foluble in water in the pro- 
portion of one part in feven or eight hundred. Calca- 
reous nitre and muriated calcareous earth are alfo 
occafionally found in fprings. 

6. Sulphur. Many waters feem by tlieir ofFen- 
livc fmell to contain fulphur, though very few of 
them, upon more accurate examination, are found 
CO afford it. The waters generally called fulphurcous 
or hepatic, are only impregnated with fulphurcous 
or hepatic gas, which is a folution of fulphur in in- 
flammable air. This is the fame gas which rifes from 
liver of fulphur, and liver of fulphur itfelf has been 

" dctefted in a very minute quantity m mineral waters. 
Sometimes bitumens are met with in mineral wa- 
ters, and commonly d^ake their appearance on the 

7. Metals. Of thefe iron is moft frequently 
found in water, fometimes c6pper, and more rarely 
zinc. Waters which contain iron are called chaly- 
beates, and are very common. 

It was formerly imagined that iron was fufpcndcd 
in mineral waters by means of the vitriolic acidj but 
M. Monnct has afcertaincd, that very few of them 
contain vitriolic acid, and that the carbonic acid» 
or fixed air, is almoft the only medium by which . 
the iron is fufpendcd. The carbonic acid is fome- 
times in excefs, fo as to render the chalybeate water 
acidulous, in other inftances it fufpends the iron 
without being in excefs. Chalybcates may, in ge- 
neral, be known by the yellow ochry fediment dc- 


574 -Wi?ii of analyzing ^Book VII. 

policed in their courfe, and alfo hj ffaiking i 
purple colour widi dccodion of galls. 

In examining any mineral waters, the firft objcft 
of attention is, to have the water as frefii as pof- 
iible, fmce, if it contzuns any volatile matters, they 
will foon fly offl A great number of trials ait 
therefore to be made on the fpot. The contents of 
the neighbouring ftrata, particularly of any high 
ground, from which the water feems to proceed, 
arc alfo to be regarded, as they often fcrve to ac- 
count for the properties of mineral waters. 

One of the moft obvious circumftanccs to be at- 
tended to is the degree of the heat of the water, 
and for this purpofe it is neccflary to be provided 
with an accurate thermometer. There are many 
fprings which have a temperature a little above 
the medium temperature of the atmofphcre, though 
this may not be fo remarkable as to have obtained 
them the name of hot fprings. The middle tem- 
perature of thcfc fprings is found to be about forty- 
eight degrees, but on elevated fituations it is Icfs, 
in proportion to their height above the fea. It 
may alio be proper t j compare the temperature of 
thefe mineral Iprings with that of fome common 
fprings in the neighbourhood. The fenfible qualities, 
as the colour, tafte, and fmell, are to be obfervtd. 
In order to difcover whether any elaftic fluid elcapcs 
from it, and of what nature it is, let fome of the 
water be put into a bottle, and a bladder tied about 
its neck. The air which efcapes may be fubmit- 
ed to examination. In order ro obtain it, it is only 
neceflfary to tie anodier firing above the bottle, and 
then to cut between them,fo as to (cparatc the blad- 
2 dcr^ 

Chap. 8.3 Mineral Heaters. ^y^ 

der, which may be plunged in water or mercury, and 

its contents received in the pneumatic apparatus. In 

order to fcparatc all the air from water, it muft 

be heated nearly to its boiling point, which may 

^afily be done by immerfing it in a veficl of boiling 

water, while it is contained in the bottle to which 

the bladder is annexed. The elaftic fluids, which 

may be feparated from mineral waters, are chiefly 

two, carbonic acid gas, and falphureous gas. It is 

proper to obfcrve the changes which are Ipontane- 

oufly produced on mineral waters by difierent 

degrees of heat. If any matter is depofited during 

• the evaporation of the mineral water, it muft be 

collefted for further examination. 

With refpeft to the addition of certain foreign 
fubftances called re-agents, to difcover tlic contents 
of mineral waters, it may in general be remarked, 
that this mode is lefs certain than evaporation; the 
latter method, however, is not free from objedions, 
as the application of heat to any body not unfre- 
quently deranges the previous ftate of combination 
among its component principles. The chemical 
tefts beft adapted to the difcovery of the contents of 
mineral waters arc the following: lime, volatile 
alkali, fixed alkalies, vitriolic acid, tinftureof turn- 
fole, muriated barytes, acid of fugar, arfenic, Pruf- 
fian alkali, and the nitrous folutions of filver and 
mercury. When ititpropofed to difcover the con-^ 
tents of a mineral water, it is beft to begin with 
fuch tefts as arc leaft capable of altering it, and 
afterwards, having obferved their efiefts, to proceed 
to compete theanalyiis by tefts which have a more 
ixtenfive influence. Lime water feizes the carbo- 

576 Chemical "Tefts [Book Vil. 

nic acid, and forms a precipitate of chalk; it alio 
precipitates falts with the bafis of clay and magncfia, 
as^ well as the metallic falts. If after mixing an 
equal quantity of lime water with a mineral water, 
no precipitation takes place in twenty- four hours, 
it may be concluded, that it contains neither carbo- 
nic acid at liberty, nor a combination of that add 
with fixed alkali, nor earthy falts with the bafis of 
aluminous earth or magneHa, nor any metallic ialt. 
But if a precipitation takes place on the addition of 
lime water, the next ftcp is to examine the proper- 
ties of the precipitated m^ter ; if it has the proper- 
ties of chalk, fuchas infipidity, the producing of an 
efiervefccnce with vitriolic acid, and forming with 
it a compound nearly infoluble in water, that is gyp- 
fum, it muft be concluded that the water contained 
carbonic acid, which, uniting with the lime of the 
lime water, produced chalk. If, on the contrary, the 
precipitated nvatter is fmall in quantity, and Aibfides 
very flowly; if it does not effervefcc, and affords 
with the vitriolic a? id a ftyptic fait, it may be con- 
cluded that it is alum, and that the mineral water 
contained clay: If a bitter and very foluble (alt is 
formed on the addition of the vitriolic acid, it is the 
Epfom fait, and the water contained the earth of 
magnefia. If the addition of vitriolic acid to the 
preci{ itatc produces fal martis, the water held iroa 
4n folution. 

The addition of cauftic volatile.alkali will ad like 
lime water, except that it will not produce a pre- 
cipitation from the prcfcnce of uncombined carbo- 
nic acid in the water; the compound formed by vo- 

Chstp. t.] far MsnUrai PTat&y. J77 

katile alkali with that acid not being infolublcj like 
the ichalk Untied by the tlnion of carbonic acid 
with lime. But befides the aluminous^ the magne- 
lian^ ind th« knetallic ialts, the cauftic voladle aU 
kali will decbmpofe thofe which have lime for their 
fxUk> and thus ve advance one ftep further in th^ 
analj^fis df the wateh The Pruffian alkali pi:ecipi*» 
tates the combinations of tarbonic and vitriolic actd 
with chalk. The nitrous folutions of (liver and 

•" mercury decompoie aJl the muriatic and vitriolic 
lalcs^ whiek may be various both in quantity and 
in kind. In thefe cafes the muriatic or vitridic 
iacid contained in the : mineral wattr, feizes the 

^•tilvcr CM" the mercury^ and forming with it an info- 
luble compound, falls to the bottom in a thick 
doud> while the nitrous acid unites with the bails 
which is deferted by one or both of the'odier acids* 
It is not neceflary in this place to enter into a 
minute cktail of die methods of diftinguifhingthe 
difference of the precipitates^ according as the 
knuriatic or vitriolic acid was conoerned m their 
produ6tion> but I fhall refer jthe reader for infor«» 
Imation on this point to what was ftated when 
treadng of the combinations of fUver aqd mercury 
V^ith the diflerent mineral acids. 

By tindhire of tumfole the predominance either 
of an alkali or an acid is diicoveTedi as vegeuble 
blues are turned red by acids> and green by alka- 
lies. Acid of fugar is a very fenfible teft of lime> . 
vrhta combined with the (parry or acetous acids. 
A felution of arlenic in the marine acid will preci- 
pitate fulphur &om water^ in which it is held dif- 
V^L. U. P p folvctf 

( 57* Cekhratei Mineral Waters. [Bodk Vft.. 

folved by means of carbonic acid. It may be added, 
that white arfenic beconnes yellow if immcrfel m 
water containing hepatic gas ; and a piece of po- 
lilhed iron will receive a copper-colour from wan 
in which copper is diflblved. If a mineral water is 
found CO contain a fixed alkaU, it may be deccr- 
mined whether it is the vegetable or mineral ilkaE 
by means of vinegar. Widi vegetable alkali vine- 
gar yields a deliquefccnc (alts with the nuneral^ 
foliated cryftals. 

It may be proper briefly to notice the compofidoa 
and obvious properties of fome of the nx)ft 
celebrated mineral waters, and the dilbrden ia 
which they are fuppofed to have moft efficacy. 

^ Aix-la-Chapelle.— This place has long beea 
famous for its hot fulphureous waters and badis. 
They arife from feveral fbarces> which iupply cig^ 
, baths conftruded in different parts of the lown. 
Thefe waters near the fources are clear and pc^ 
lucid, and have a ftrong fulphureous finell re- 
fembling the wafhings of a foul guns but they lofe 
this fmell by expofure to air. Their tafte is &lioc> 
bitter> and urinous. They do not contain iron. 
They are alfo neutral near the fountain, but after- 
wards are manrfefUy, and pretty ftrongly alludine, 
infomuch that doaths may be wafiied with cfaem 
withput foap. The gallon contains about two fcru- 
pies of fea fait, the lame quantity of ehalk> and 
a dram and half of natron. They are at fiift 
naufeous and harfli, but by habit become £umliar 
and agreeable. At firft drinking aUb they generaHy 

fchap. 8,] Aix'-la-Cbapette and Bath. 579 

^aficft the head« Their general operation is cathar- 
tic and diuretic^ without griping or diminution of 
ftrengthj and they alfo promote pcrfpiration. 
The quantity to be drunk as an alterative, is to 
be varied according to the cohftitution, and other 
circuniftances of the patient. In general, it is befl: 
CO begin with a (|u^rter> or half a pint in the morn- 
ing, and increaie the dofe afterwards to pbts, as 
may be found convenient. The water is bell 
drunk at the fountain. When it is required to 
pyrge, it ffaould be drunk in large and often re-* 
peated draughts *.' 

The heat of the different baths of the Aix-la- 
Chapelle waters varies from one hundred and fix of 
Farcnheit's thermometer to one hundred and thirty. 
In bathing it is proper to begin with the moft tem- 

* Bath has long been famous for its warm 
chalybeate waters. There are feveral fprings, but 
their waters are all of the fame nature. There ard 
fix baths J but the principal are the King's bath, 
the ^een's bath, and the Crofs bath. The others 
are only appendages to thefe. The two former 
raife the thermometer to 11 6% the latter to 112*. 
The water when viewed in the baths has a greenilh,* 
or fea colour: but in a phial it appears quite tranf- 
. parent and colourlefs, and it fparkles in the glafs. 
It has a very flight faline, bitterilh, and chalybeate 
tafte, which is not difagreeable, and fbmetimes 
feme what of a fulphureous fmell; but this latter 

* Elliot on Min. Waters, p. 119, &c. 

P P a ii 

5 8o Bath and ErijioL ' [fiook VH* 

is ttot nfoafiy perceptible, except when the bach» 
are filling. The gallon o( Bath water contains 
twenty-three grains of chalk, the fame quantity of 
muriat of .magnefia, tliirty-eig^t of fca lalt, and 
8. 1 of aerated iron* As it rifes from the pump, it 
contains fixed air, or other volatile acid, in a fuP* 
ficienc quantity to eurdle milk and aft npon iron. 
The Bath water operates powerfully as a diuretic, 
and promotes perfpiration-r If drunk quickly, in 
large draughts, it fometknes purges ; but if ^en 
flowly and in fmall quantity^ k rather has the con- 
trary efFcft. An heavinefs of the head, and incli- 
nadon to deep/ are ofi:en felt on firft drinking it */ 

This water when taken inwardly is fiiid to give 
a ftimulus and vigour to the whole conftitrftion, i& 
therefore proves ufeful in oW rheumatic complaints, 
and in cafes of gout conncfted with much debility. 
During the ufe of the Bath water, and Ibmc dme 
previous to it, the patient (hould live on a light diet, 
eafy of digeftion. The courfe fhould be continued 
for a month or fix weeks. In local complaints, as 
in ftifi^ joints and chronic pains, the application of the 
water by pumping is more cfficrxious than bathing 
the whole body. 

Bristol, * The fprings are known by the name 
of the Hot Wells. The water at its origin is warm, 
clear, pellucid and fparkling j and if let ftand in a 
glafs, covers its infide with fmall air-bubbles. It has 
BO fm^ell, and is foft and agreeable to the tafte. It 
laifes the thermometer fi-om about fcventy to eighty 

• Elliot onMin. Waters, p. 134, &c. 


Ch^. 8 .] Buxfm fFafers. 581 

degrees. It contains la^ grains of chalk, 5^ 
of muriat of magncfia, and 64. of fca fait in the 

The Brift^l waters arc particularly recommended 
in pulmonary complaints ; the fame, however, of 
Brill ol has probably been more owing to the mild- 
hefs of the air in that part of England^ than to the 
virtues of its waters. 

Buxton. — ^ This is a hot water, refcmbling that 
of BriJioL It raifcs the thermometer to 8 1** or 82**. 
It has a fweet and pleafant tafte. It contains a 
little calcareous earth, together with a fmall quan- 
tity of fea falt> and an inconfiderable portion of a 
cathartic fait. Iron has been difcovered in it, but 
in fo extremely fmall a quantity as not to defcrvc 
notice ; and even that perhaps owing to accident. 
This water taken inwardly is cfteemed good in the 
diabetes; in bloody urine; in the bilious cholic; 
in lofs of appetite, and coldnefs of the ftomach ; in 
itiward bleedings; in atrophy; in contradlion of the 
veffels and limbs, efpecially from age; in cramps 
andconvulfionsj in the dry afthma without a fever ^ 
and alfo in barrennefs. Inwardly and outwardly ic 
is faid to be good in rheumatic and fcorbutic com- 
plaints; in the gout; in inflammation of the liver 
and kidnies, and in confumptions of the lungs ; 
alfo in old drains; in hard callous tumours; ia 
withered and contrafted limbs; in the itch, fcabs, 
nodes, chalky fwellings, ring-worms, and other 
Gmilar complaints. Befides the hot water^ there is 

* Elliot on Miiu Waters^ p. 145, kc. 

Pp3 alfo 

5? a Cbeltenbam and Epfom. [Book VII, 

alfo a cold chalybeate water, with a rough irony taftc. 
It rcfembles the Cawtborp water*/ 

* Cheltenham, /» Gkucefierftnrey is one of 
the beft and moft noted cathartic chalybeate watcn 
in England, though it is not fo much frequented 
as formerly. The gallon contains eight drams of 
a cathartic fait, partly vitriolated natron, paitly 
vitriolated magncfiai twenty- five grains of magnefia, 
part of which is united with marine, part with aerial 
acid; and nearly five grains of iron combined with 
aerial acid. It alfo yielded thirty-two ounce ipeafurcs 
of air, twenty-four of which were fixed air, the reft 
azotic with a portion of hepatic air. The doie is 
from one pint to three or four. It operates with 
great eafe, and is never attended with gripings, 
tenefmus, &c. It is beft taken ^ little warm. 
It alfo creates an appetite ; is excellent in fcorbutic 
complaints, and has been ufed with fuccefs in the 
gravel. As the fpring has been calculated to yidd 
only thirty-five pints of water an hour, without 
frugal management there would not be enough to 
Supply the demands of the drinkers. The Walton 
water has lately been recommended as a fubftitutc 
to obviate this inconvenience.' 

Epsom, x» ^i/rry. — The water has a flight falinc 
tafle, is clear, and without fmell. But if it is kept in 
covered veffels for fome weeks in the fumixierit will 
ftink, and acquire a naufeous and faltifh bitter tafte. 
This was the firft water froni which the fait thence 
called Epfom Jalt was obtained. But the lalt ufual)/ 
fold by that name is different from diat yiddcd 

f Elliot on Min. Waters, p. ici, &c. 

Ghap. 8.] Hamnvgate and Matlock. 583 

by the Epfom water, though perhaps not inferior 
in virtue. - It is made from the bittern left after 
the cryftallization of common fait from fea water. 
The Epfom water is cathartic; for which purpofe 
it muft be drunk to the xjuantity of two or three 
pints. It is alfo diuretic. 

Harrowgate.-' There are four fpnngs at this 
place, but the waters of all of them are nearly alike, 
except ii» the quantity of the faline matter they con- 
tain. Of the three old fprings, the higheft gave 
three ounces of folid matter.; the loweft, an ounce 
and an half; and the middle one, only half an ounce. 
Of the latter one hundred and forty grains were 
eart'i The water as it fprings up is clear and fpark- 
ling, and throws up a quantity of air-bubbles; 
It has a ftrong fmell of fulphur, and is fuppofed to 
be the ftrongeft fulphureous water in En^d. 
It has a fait tafte, as it contains a confiderable 
quantity offea fait, together with a little marine falc 
ofma^nefxa, and calcareous earth *.' 

Harrowirate water is cathartic when taken m 
dofes of feveral pints. When ufed externaUy as a 
fomentation, it is faid to be ufeful in fonnc difordere 
of the (kin; and by fome phyficians it is confidcred 
as efficaceous in dcftroying worms. 

Matlock. -« At this place (which is perfeftly 
romantic) are feveral fprings of warm water, which 
appear to be of the nature of the Bn>/ water, ex- 
cept that it is very ttightly impregnated with iron, 
its heat is about 6^% and its virtues are fimilar to 

• Emot,p. 177 and '84- 

p p 4 thoft 

584 Pyrwrni Waters. [BookVll^. 

thofe of the £r{^(?/ and JSkx/^ waters. The bathsi 
^re recommended in rheuniiacic oomplaio^ ia 
cutaneous difbrders, and in other cafes where warm 
bathing is ferviceable. There are great numbers 
of jpetrifaftions in the courfe of this water */ 

Pyrmont, in ff^eftpbalia.—^ This is a very hciO^ 
chalybeate^ abounding in fixed airi and when cakei^ 
up from the fountain^ fparkles like the brifkeft 
Champaign wine* It has a fine^ plea^nt^ vinOu^ 
tafte^ and a fomewhat fulphiueous firiell. It i$ 
perfedly clear^ and bears carriage better than the 
Spa water, A gallon of it contains 46 grains of 
chalk, 15.6 of magnefia, 30 of vitriolated magnefia, 
10 of fea fait, and 2.6 of aerated iro|i-|'. Ferlbns 
who drink it at the well, are afieded with a kind 
of giddinefs or intoxication y owiog9 it may bo 
fuppofcd, to the quantity of fixed air with which 
the water abounds. The common operation of this 
water is diuretiq; hut it is aifo gendy fudorifici 
and if taken in large quandtjr proves cathartic^ 
When, however, it is required to havp this latter 
eifedji it is uieful to mix fome falts with the firft 
glaflfes. It is drunk by glafsfuk in the monung^ 
to the quantity of from one to five or fix pints^ 
according to circumftapceSj walking about b^tw^ei) 
each glafs;):/ 

* Elliot;* p. flio. 

f Dr. Marcard, in his DtJtripUm offjrmona^ 00 ^ aotho* 
rity of M. Weftrumb of Hammcln, eftimates the irpa at fome* 
what more than eight gratis to tl^e g^Uoa^ 

\ Elliot, p. 2s6« 


Clhap. 8.3 Scarhercugh Heaters. 58$ 

Pyrmont waters arc recommended in debilitated 
and relaxed conftitutions, attended with indigeftion, 
low ipirits, and want of api>etite. 

Scarborough, in Torkjhire. — * The waters of 
this place are chalybeate and cathartic; and they 
are more frequented and ufed than any other water 
of this clafs in England. There are two wells i the 
one more cathartic, the other a ftronger chalybeate. 
Hence the latter (which is neareft the town) has 
been called the chalybeate fpring, the other the 
purging; though they are both impregnated with the 
fame principles, but in different proportions. The 
purging is the moft famed, and is that which is 
ufually called the Scarborough water. This con- 
tains fifty- two grains of calcareous earth, two of 
ochre, and two hundred and fixty-fix of vitrtolatcd 
magn^Qa, iii the gallon: the chalybeate, feventy 
grains of calcareous earth, one hundred and thirty- 
nine of vitriqlated magnefia, and eleven of fea fait* 
When theft waters arc poured out of one gla6 
into another, they throw up a number of air-bub- 
\)ksi and if fliaken for a while in a clofe ftopt phial, 
and the phial i? fuddeply opened before the com- 
motioDxCeafes, they difplodean elaftic vapour with 
an audible noife, which fliows that they abound in 
fixed air. At the fountain they both have a briflc, . 
pungent, chalybeate taft^i but the cathartic water 
taftes bittcrifh, which is not ufually the cafe with the 
(halybeate. They lofe their chalybeate virtues by ex- 
pofurc, and alfo by keepings but the cathartic water ^ 
fooneft. They both piKrify by keeping! but in 
tjipp recover their fweetnefs*.' 

t plUot,p.a3^t 

1 8 5 Scarborough and Spa. [Book VII. 

The properties of the cathartic and of the chaly- 
beate fpring are, as might naturally be fuppofcdjV^ry 
different. The former is ufefql in cafes of habituaf 
coftivenefs^ the latter in difordprs of relaxation ancj 

Spa, in the bijhopric of Liege. — ' In and about this 
town there are feve^-al fprings, which afford excel- 
lent chalybeate waters : and in Great Britain they 
^re the mofl in ufe of any foreign mineral waters. 

* The principal fprings are, i. The Pobowtj or 
Pouhon^ fituated in the middle of the village; — 2. 
Sauvinierfi about a mile and an half eaft from it;— 
3. Groijbeecky near to the Sauviniere;— 4. Tonnelet^ 
^ little to the left of the road to the Sauviniere ; — 5. 
fTalroz, near to the Tonneleti — 6. Geronjiere^ two 
miles fouth of the Spa; — 7. Sorts, or Nrverjet, in 
the diftridt of Sarts ; — %. Chevron^ ot BrUj in the 
principality of Stavelot; — 9. Couve, — 10. Beverfee^ 
—II. Stge, — 12. Geromonty all near Malmdy. . 

* The Potihon is a flow deep Ipring, and is 
more or lefs ftrong or gafcous according to the flatc 
pf the atmofphere, The gallon contains ten grains 
pf chalk, diirty of magnefia, ten of natron, and five 
of aerated iron. It yields of fixed air one hundred 
and thirty-two ounce meafures. It contains more 
iron than any of the other fprings, and does not 9^ 
foon lole its gas. It is in its mofl perfeft and natu- 
ral ftate in cold, dry weather. It then appears co- 
lourlefs, tranfparent, and without fmell, and has a 
fubacid chalybeate tafle, with an agreeable fmarc- 
ncfb: at fuch times, if it is taken out of the well 
in a glafs^ it does not fparkle; but after (landing a 


Chap. «.] Spa Waters. 587 

-while, covers the glafs on the infidc with finall air- 
tubbles 5 but if it is fhaken, or poured out of one 
glafs into another, it then fparkles, and difchargc^ 
^ great number of air-bubbles at the furfacc. In 
waf m, moift weather, it lofes its tranfparcncy, ap- 
pears turbid or wheyifti, contains lefs fixed air, and 
IS partly decompofed. A murmuring noife alfo isf . 
fometimes heard in the well. It is colder than the , 
heat of the atmofphere by many degrees. It i$ 
fuppofed to contain the greafeft quantity of fixed 
air of almoft any acidulous. water; and confequent- 
ly has a remarkable fprightlinefs and vinofity, 
a:nd boils by mere warmth. This, however, foon 
flies ofF, if the water is left expofed; though in well 
forked bottles it is in a great m-cafure preferved, 
It is capable of diflblving more iron than it naturally 
contains, and thus becorning a ftronger chalybeate. 
This is owing to the great quantity of fixed air 
which it contains. For the fame reafon an ebul- 
lition is raifed in this water on the addition of 
acids, as they difengage its fixed air. It mixe^ 
fmoothly with milk, whether it is cpld or of 4 
boiling heat. 

* Of the Sauviniere water, a gallon yields 6,c 
grains of chalk, 4.5 of magnefia, two of natronjj 
3.5 of kali, 2.1 of aerated iron, and 108 ounce 
meafures of fixed air. At the w^l it has fomewhaf , ) 

a fmell of fulphur. 1 

^Groijbeeck. The water is of the fame na- j 

ture as the Sauviniere, but contains a fomewhat 
larger proportion of the feveral ingredients. It has a 
yitriolic tafle, and fomewhat of a fulphiireous fmelK 

5t8 Spa [Boc&lVIL 

' Tcmalet. This is one of the mo&^^Highdf 
waters in the world. It is much colder than citfacr 
of the other Spa waters; has no fmell i is bright, 
traniparentj and colourlefs; and fit>m the rapidir^ 
of its motion does not foul its bafbn. It has a 
fmart, fubacid^ fprightly tafle^ not unlike the briik- 
eft Champaign wine. From a variety of cxpeii- 
ments it appears, that this water is more ftrongly 
charged than any of the others with fixed air^ on 
which the energy of all waters of diis kind prindpal* 
ly depends, but it parts with it more readily. It 
contains more iron dian any of the fpringst except 
the Pouhon, 

< fF^troz. Its (ituation is loweft of any of the 
fprings about Spa, and it is nmre apt to befoul ; 
but when the well is cleaned out, aiid the water 
pure, it is found to be of the fame nature as that of 
Pouhon. It is not cathartic, as fome have aliened. 

* Gerenftere. This water has much lefs fixed 
Hir than the Pouhon. It has a fulphureous fmeU 
at the fountain, which it lofes by being carried to 
a diftance. This fmell is fbongeft in warm moift 
weather. The air, or vapour, of this water aflefts 
the heads of fome who drink it, occafioning a gid- 
dincfs, or kind of intoxication, which goes off in 
a quarter or half an hour. The Pyrmont, and fcve- 
ral other brifk chalybeate waters, arc found to 
have the fame effeft. It is colder than any of die 
fprings, the Tonnclct excepted. 

• Sarts^ or Niver/et. It refembles the Ton, 
ndet water, but is rather lefs brifk and gafeous. 
It is however more acid and flyptic. 

Chap.S.] fTat^s, 5«9 

« BrUi or Chevrm. The phyficiafls at Liege 
have artfully decried this water, becaufe it is not 
in the prineipality of Liege. But by erery trial it 
appears not much inferior to any of the Spa waters* 
In the quantity of fixed air and of iron it contains^ 
it approaches the Pouhon* 

* Couvi and Beverjee. The Couve nearly re-^ 
femblcs the Tonnelet water; or rather, may be 
placed in a medium between that and the Watroz^ 

• It hardly equals the tranfparenCy, fmartnefs, and 
generous vinous tafte of the firli, but it greatly fur- 
pafles the latter. The Beverfee agrees with this, 
only that it does not retain its fmartnefs fo well by 

* Lti Slge. It has fomc of the general pro- 
perties of the Spa waters, but in other refpefts it i% 
different. It is moderately fubacid, fmaft, and 
grateful, but has no fenfibk chalybeate tafte. It 
i^arkles like Champaign when poured from 
one glafs to another. Upon (landing it lofes its 
fixed air, and throws up a thick mother-of-pearl 
coloured pellicle. It is much more loaded with 

* earthy matters, and lefi impregnated with iron and 
fixed air, than the other Spa waters. 

« Geromont. As a chalybeate and acidulous 
water it feems to be nearly of the lame ftrength 
with La Sige ; but it contains a greater quantity of 
natron, together with a mixture of fea falc. The. 
earthy nriatters, however, are lefe.' It appears^ 
that thefe waters are compounded of nearly the 
fame principles, though in dilTercnt proportions. 
All of them abound with Jixci air. They con- 

J56 spa Waiers. ^ [Book VII* 

kairt more or lefs iron, natron, and calcareous and 
fclcnlrical earths; together with a fmall portion of lea 
fait. Thefe arc all kept fufpcndcd, and in a neutral 
ftate, by means of the aerial acid, or fixed air. 
From a review bf the contents of thefe waters, it 
cannot be imagined that their virtues principally 
depend on the fmall quantity oi folid matters which 
they contain. They muft therefore depend moftly 
on their fixed air. And they arc probably ren- 
dered more adivc and penetrating both in the firft 
paflages, and alfo when they enter the circulation, 
by means of that fmall portion of iron, earthy 
fait, &c. with which they are impregnated *. ' 

After all that has been alleged in favour of mi- 
neral waters,, it muil be confeifed diat their medical 
virtues are at bcft rather dubious. With refpcft to 
the metallic falts which they may contain, the quan- 
tity is too minute to be very efficacious inobftinatc 
complaints; and the warm baths have probably no 
other cfFeft than a quantity of common water heated 
to the fame temperature would have, if applied by 
means of an artificial bath at home. Where good 
ieffcds have been wrought upon a patient's referring 
to a mineral water, phyficians have overlooked the 
excellent confequcnces which in the common courfc 
of things might be expe^ed from the exercife of the 
journey, the change of air, and change of fccne, 
from cheerful company, and, though laft, not Icaft, 
perhaps, from the imagination of the patient. 

• See EUiot, p. 249, &c. 


i 59^ 1 




isTiLLED water looo 

Calcareous Earth 27I3 

IVIagneiian earth £155 

Barytic earth - 3973 

Argillaceous earth - 1669 

Siliceous earth - 2650 ' 

Bottle glafs - 2732 

White glafs - 2892 

Flint glafs - - J329 

Seves porcelain • 2145 

China ditto - 2384 

Lime flonesy from - 1386 

■ — to - 2390 

Common flate - 2672 

Mufcovy talk - 2792 

Calcareous fpar - 2715 

Fluor fpar - - 3180 

White marble - 2716 

Diamond . - . 3445 

Ruby - * - 42^3 

Topaz - - - 3460 

Emerald ... 3600 

Hyacinth ... 3764 , 

Garnet - - - . 3978 

Tourmaline - - 3050 

Opal . - - - 2764 

Cat's eye - - . 2240 

Onyx - - - . 2600 

Carnelion - - ^ - 2704 

Common flint - - 2700 

Jafper - - - - 2778 

Quartz - - - - 2654 

Agate - • - - 2590 

Gold - - - - 19640 

Platina - - - 22000 

Mercury - - - 13568 

Lead - - - - 11352 

Silver - - - - ^0474 

Copper - - - 


Iron . - - - 


Tin . . i . . 


Bifmuth - - • 


Nickel .... 


Arfenic ... 


Zinc .... 


Antimony - - . - 


Rlanganefc ... 


Cobalt - . . ^ 


Tungftcin . - - 


Molybdena - - 


Vitriolic acid - - 


Nitrous acid - - 

Muriatic acid - - 


Fluor acid ... 


Oil of olives <• - 


Linfeed bil . - - - 


Burgundy wine • - 


Bourdeaux ditto 


M.ilmfey madeira ." 


Cyder .... 


Woman's milk - . 


Mare's milk - - 


Cow's milk - 


Goat^smilk - - '- 


Ewe's milk 


Elallic gum - - - 


Naptha . - . - 


Camphor -' - . 


Spermaceti - . - 


Tallow - . . . 


Vitriolic aether - . 


Nitrous aether - 


Muriatic aither - - 

• 730 

Acetous aether - - 


Pureftfpiritof wine 

- 820 





Table of the weights of the diffemit gafies at 29. %J^. tt^ 
. )ilh inches, haiometrical preiFore, and «t 54. 5* of tempera- 
tare, according to Fahrenheit's thennometer, ezprc&dm 
Englifh meafore, and Engliih troy weight* From Lavd- 
fier's Cheiniftr]r.-^The weight of the five bSt wereaiceiw 
tained by M. Lavoilier himfelf; the laft three were ioiertti 
by M« LaToifier on the authority of Mr. Kirwaii* 

«—•'.>*' T^^ 

Weight of a 

MB. /r. grt. 

Atniofpheric air - . 32119 

1 I «S 

Azotie gas ^ - - • • 50064 * 

I 39 

Oxygeagas - • . 34211 

I « 5» 

Hydrogen gas «* - • 02394 


Cafbontc acid gas * * 441^8 

1 4 4« 

Nitrons gas - - - . 37000 

I t 39 

Ammoniacal gas • • x^SiS 

5 19 

Sttlphnreous aeid gas . 7is9o 

a 4 i^